Method of and system for recording image information and method of and system for encoding image information

ABSTRACT

A digital video data recording system has a signal source, a motion detector, an external memory for storing motion vector data, an encoder, a recorder, and a controller. The controller obtains motion vector data and quantization step size data in a preprocessing procedure, and encodes image data using the motion vector data read from the external memory and the quantization step size data and records the encoded image information on a recording medium in a recording process. The digital video data recording system can encode image information appropriately depending on the type of the image information, minimizes the consumption of electric energy by not effecting a motion detecting process in the recording process, and can record all the image information to be recorded on the recording medium.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of and a system for recordingimage information in a transmitter of an information transmissionapparatus, a recording apparatus having a disk or a magnetic tape as astorage medium, a disk manufacturing apparatus such as a stamper for anoptical disk, or the like, and a method of and a system for encodingimage information.

2. Description of the Related Art

Transmitters of information transmission apparatus, recorders ofrecording and reproducing apparatus having a disk or a magnetic tape asa storage medium, signal processors of disk manufacturing apparatus suchas a stamper for an optical disk incorporate an encoder as shown in FIG.1 of the accompanying drawings, for example. The encoder as shown inFIG. 1 is in accord with the moving picture image encoding standards forstorage which have been established based on standardizing efforts madeby the MPEG (Moving Picture Image Coding Experts Group).

FIG. 1 shows an internal structure of an image encoder.

As shown in FIG. 1, the image encoder has an input terminal 400 which issupplied with image data from a signal source (not shown). The inputterminal 400 is connected to a first input terminal of a motion detector421, an input terminal of a motion compensator 424, and an inputterminal of a frame memory 422. The frame memory 422 has an outputterminal connected to a second input terminal of the motion detector421, an input terminal of a frame memory 423, an additive input terminalof an adder 427, an intraframe fixed contact "b" of a switch 428, and aninput terminal of an inter-/intra-frame decision unit 429. The framememory 423 has an output terminal connected to a third input terminal ofthe motion detector 421 and an input terminal of a motion compensator425. The motion compensator 424 has an output terminal connected to anadditive input terminal of an adder 426 which has a 1/2 multipliertherein. The motion compensator 425 has an output terminal connected toanother additive input terminal of the adder 426. The adder 426 has anoutput terminal connected to a subtractive input terminal of the adder427. The adder 427 has an output terminal connected to an inter-framefixed contact "a" of the switch 428 and another input terminal of theinter-/intra-frame decision unit 429. The switch 428 has a movablecontact "c" connected to an input terminal of a DCT (Discrete CosineTransform) circuit 430 whose output terminal is connected to an inputterminal of a quantizer 431. The quantizer 431 has an output terminalconnected to an input terminal of a variable length coder 432 whoseoutput terminal is connected to an input terminal of an output encoder433. The output encoder 433 has an output terminal connected to anoutput terminal 434. The motion detector 421 has an output terminalconnected to other input terminals of the motion compensators 424, 425and another input terminal of the variable length coder 432. The framememories 422, 423 and the inter-/intra-frame decision unit 429 areconnected to a controller 435.

The frame memories 422, 423 read and write frame image data according toread/write control signals R/W which are supplied from the controller435.

At the time frame image data have been stored in the frame memory 422,if the frame memory 422 outputs frame image data of a present frame,then the input terminal 400 is supplied with frame image data of afuture frame, and the frame memory 422 stores frame image data of a pastframe. The present frame will be referred to as a "present frame", thefuture frame as a "following frame", and the past frame as a "precedingframe".

The motion detector 421 effects a motion detecting process on eachmacroblock having a size of 16 lines×16 pixels, for example, withrespect to frame image data supplied through the input terminal 400,frame image data read from the frame memory 422, and frame image dataread from the frame memory 423. The motion detecting process may be awell known motion detecting process based on full-search block matchingprinciples, for example.

Specifically, the motion detector 421 detects a motion with respect tomacroblock data MB(f) of the present frame stored in the frame memory422 and macroblock data MB(f+1) of the following frame supplied throughthe input terminal 400, and produces motion vector data MV based on thedetected motion, and also detects a motion with respect to macroblockdata MB(f) of the present frame stored in the frame memory 422 andmacroblock data MB(f-1) of the preceding frame stored in the framememory 423, and produces motion vector data MV based on the detectedmotion.

A single signal line is shown as being connected to the output terminalof the motion detector 421, and only one symbol "MV" is used to indicatemotion vector data. Actually, however, the motion detector 421 producesin each of the above motion detecting cycles as many motion vector dataMV as the number of all macroblocks of the frame image data stored inthe frame memory 422.

Based on the motion vector data MV supplied from the motion detector421, the motion compensator 424 extracts the macroblock data MB(f+1)which are closest to the macroblock data MB(f) to be processed of thepresent frame, from the frame image data of the following frame suppliedthrough the input terminal 400, and supplies the extracted macroblockdata MB(f+1) to the adder 426.

Based on the motion vector data MV supplied from the motion detector421, the motion compensator 425 extracts the macroblock data MB(f-1)which are closest to the macroblock data MB(f) to be processed of thepresent frame, from the frame image data of the preceding frame storedin the frame memory 423, and supplies the extracted macroblock dataMB(f-1) to the adder 426.

The adder 426 adds the macroblock data MB(f+1) from the motioncompensator 424 and the macroblock data MB(f-1) from the motioncompensator 425 and multiplies the sum by "1/2", with the 1/2 multipliertherein, thereby producing average data representing the average of themacroblock data MB(f+1) from the motion compensator 424 and themacroblock data MB(f-1) from the motion compensator 425.

The adder 427 subtracts the average data supplied from the adder 426from the macroblock data MB(f) of the present frame supplied from theframe memory 422, thereby producing differential data between themacroblock data MB(f) of the present frame and the macroblock datarepresented by the average data produced by the bidirectional predictiveprocess.

The inter-/intra-frame decision unit 429 connects the movable contact"c" of the switch 428 selectively to the inter-frame fixed contact "a"or the intra-frame fixed contact "b" thereof based on the differentialdata from the adder 427, the macroblock data MB(f) from the frame memory422, and a frame pulse Fp supplied from the controller 435. Theinter-/intra-frame decision unit 429 also supplies an inter-/intra-frameselection signal SEL indicative of a controlled state of the switch 428to the controller 435. The inter-/intra-frame selection signal SEL istransmitted together with encoded image data as decoding information EDato enable a controller of an image decoder which serves as a main unitfor effecting a decoding process to switch between inter-/intra-framedata in the same manner as in the encoding process for decoding theimage data.

Details of the image encoder shown in FIG. 1 are as follows: Image datato be encoded in terms of macroblocks are the frame image data of thepresent frame which are stored in the frame memory 422. The motiondetector 421 detects motions in order to seek the macroblock dataMB(f+1), MB(f-1) of the following and preceding frames which are closestto the macroblock data MB(f) of the present frame to be encoded. Whenthe macroblock data MB(f+1), MB(f-1) of the following and precedingframes which are closest to the macroblock data MB(f) of the presentframe are detected, motion vector data MV are produced. Using the motionvector data MV, the macroblock data MB(f+1), MB(f-1) of the followingand preceding frames which are closest to the macroblock data MB(f) ofthe present frame are extracted so as not to transmit data which are incommon with the previously transmitted data.

After the differential data are produced between the macroblock dataMB(f) of the present frame and the macroblock data obtained according tothe bidirectional predictive process by the adder 427, the macroblockdata MB(f) of the present frame cannot be decoded merely based on thedifferential data. Therefore, the motion vector data MV are supplied tothe variable length coder 432, and after the motion vector data MV arecompressed by the variable length coder 421, the compressed motionvector data MV and the differential data are transmitted.

The inter-/intra-frame decision unit 429 serves to select either theencoding of the differential data or the encoding of the output datafrom the frame memory 422. The encoding of the differential data, i.e.,the encoding of differential information between frames, is referred toas "inter-frame encoding", and the encoding of the output data from theframe memory 422 is referred to as "intra-frame encoding". The term"encoding" does not signify the differential calculation effected by theadder 427, but connotes the encoding process carried by the DCT circuit430, the quantizer 431, and the variable length coder 432. Theinter-/intra-frame decision unit 429 actually switches between theinter-/intra-frame encoding processes in terms of macroblocks. However,for an easier understanding of the present invention, it is assumed thatthe inter-/intra-frame decision unit 429 switches between theinter-/intra-frame encoding processes in terms of frames.

Image data of each of frames which are outputted from the switch 428 andencoded are generally referred to as an I picture, a B picture, or a Ppicture depending on how they are encoded.

The I picture represents one frame of encoded image data produced whenthe macroblock data MB(f) of the present frame supplied from the switch428 are intra-frame-encoded by the DCT circuit 430, the quantizer 431,and the variable length coder 432. For generating an I picture, theinter-/intra-frame decision unit 429 controls the switch 428 to connectthe movable contact "c" to the fixed contact "b".

The P picture represents one frame of encoded image data that compriseinter-frame-encoded data of differential data between the macroblockdata MB(f) of the present frame supplied from the switch 428 andmotion-compensated macroblock data of an I or P picture which precede intime the macroblock data MB(f) of the present frame, and data producedwhen the macroblock data MB(f) of the present frame areintra-frame-encoded. For generating a P picture, the motion vector dataMV used to effect a motion compensating process on the image data of theI picture are generated from image data to be encoded as a P picture andimage data preceding the image data in the sequence of the image datasupplied to the image encoder.

The B picture represents data produced when differential data betweenthe macroblock data MB(f) of the present frame supplied from the switch428 and six types of macroblock data (described below) areinter-frame-encoded.

Two of the six types of macroblock data are the macroblock data MB(f) ofthe present frame supplied from the switch 428 and motion-compensatedmacroblock data of an I or P picture which precede in time themacroblock data MB(f) of the present frame. Other two of the six typesof macroblock data are the macroblock data MB(f) of the present framesupplied from the switch 428 and motion-compensated macroblock data ofan I or P picture which follow in time the macroblock data MB(f) of thepresent frame. Still other two of the six types of macroblock data areinterpolated macroblock data generated from I and P pictures whichrespectively precede and follow in time the macroblock data MB(f) of thepresent frame supplied from the switch 428 and interpolated macroblockdata generated from P and P pictures which respectively precede andfollow in time the macroblock data MB(f) of the present frame suppliedfrom the switch 428.

Since the P picture contains encoded data using image data other thanthe image data of the present frame, i.e., inter-frame-encoded data, andalso since the B picture comprises only inter-frame-encoded data, the Pand B pictures cannot be decoded on their own. To solve this problem, aplurality of related pictures are put together into one GOP (Group OfPictures) which is processed as a unit.

Usually, a GOP comprises an I picture or a plurality of I pictures andzero or a plurality of non-I pictures. For an easier understanding ofthe present invention, it is assumed that intra-frame-encoded image datarepresent an I picture, bidirectionally predicted and encoded image datarepresent a B picture, and a GOP comprises a B picture and an I picture.

In FIG. 1, an I picture is generated along a route from the frame memory422 through the switch 428, the DCT circuit 430, the quantizer 431 tothe variable length coder 432, and a B picture is generated along aroute from the input terminal 400 through the motion compensator 424,the adder 426, the output terminal of the frame memory 423, the motioncompensator 425, the adder 426, the adder 427, the switch 428, the DCTcircuit 430, the quantizer 431 to the variable length coder 432.

The DCT circuit 430 converts the output data from the switch 428, ineach block of 8 lines×8 pixels, from DC data into coefficient data ofharmonic AC components. The quantizer 431 quantizes the coefficient datafrom the DCT circuit 430 at a predetermined quantization step size. Thevariable length coder 432 encodes the quantized coefficient data fromthe quantizer 431 and the motion vector data MV from the motion detector421 according to the Huffman encoding process, the run-length encodingprocess, or the like. The output encoder 433 generates inner and outerparity bits respectively with respect to the encoded data outputted fromthe variable length coder 432 and the decoding information EDa from thecontroller 435. The output encoder 433 then adds the generated inner andouter parity bits respectively to the encoded data outputted from thevariable length coder 432 and the decoding information EDa from thecontroller 435, thereby converting a train of data to be outputted intoa train of data in a product code format. A synchronizing signal andother signals are also added to the train of data in the product codeformat.

Data contained in a GOP when it is outputted include decodinginformation, frame data of a B picture, decoding information, and framedata of an I picture, arranged successively in the order named from thestart of the GOP.

The decoding information EDa comprises GOP start data indicating thestart of the GOP, the inter-/intra-frame selection signal SEL referredto above, and other data. If the GOP start data have a value of "1",then the GOP start data indicate that the frame data with the GOP startdata added to its start are frame data at the start of the GOP. If theGOP start data have a value of "0", then the GOP start data indicatethat the frame data with the GOP start data added to its start are notframe data at the start of the GOP, but frame data at the start of apicture.

Operation of the image encoder shown in FIG. 1 will be described below.

For generating an I picture of a GOP, the inter/intra-frame decisionunit 429 controls the switch 428 to connect the movable contact "c" tothe intra-frame fixed contact "b". Frame image data read from the framememory 422 are encoded by the DCT circuit 430, the quantizer 431, andthe variable length coder 432. At this time, decoding information EDa issupplied from the controller 435 to the output encoder 433. To theencoded data from the variable length coder 432 and the decodinginformation EDa from the controller 435, there are added inner and outerparity bits by the output encoder 433, which then outputs an I picture.

For generating a B picture of a GOP, the inter/intra-frame decision unit429 controls the switch 428 to connect the movable contact "c" to theinter-frame fixed contact "a".

The motion detector 421 detects a motion successively in the macroblockdata MB(f) of the present frame and the macroblock data MB(f+1) in theframe image data of the following frame. As a result, the motiondetector 421 selects the macroblock data MB(f+1) which is closest to themacroblock data MB(f) of the present frame are selected, and producesmotion vector data MV indicative the position of the macroblock dataMB(f+1) with respect to the macroblock data MB(f). Similarly, the motiondetector 421 detects a motion successively in the macroblock data MB(f)of the present frame and the macroblock data MB(f-1) in the frame imagedata of the preceding frame. As a result, the motion detector 421selects the macroblock data MB(f-1) which is closest to the macroblockdata MB(f) of the present frame are selected, and produces motion vectordata MV indicative the position of the macroblock data MB(f+1) withrespect to the macroblock data MB(f).

The two motion vector data MV thus produced are supplied to the variablelength coder 432 and also to the motion compensators 424, 425. Themotion compensator 424 extracts the macroblock data MB(f+1) representedby the motion vector data MV, and supplies the extracted macroblock dataMB(f+1) to the adder 426. The motion compensator 425 extracts themacroblock data MB(f-1) represented by the motion vector data MV, andsupplies the extracted macroblock data MB(f-1) to the adder 426.

The adder 426 adds the macroblock data MB(f+1) from the motioncompensator 424 and the macroblock data MB(f-1) from the motioncompensator 425, and multiplies the sum by "1/2", thereby averaging themacroblock data MB(f+1), MB(f-1). The average data from the adder 426are supplied to the adder 427 through the subtractive input terminalthereof. The additive input terminal of the adder 427 is supplied withthe macroblock data MB(f) of the present frame read from the framememory 422. The adder 427 subtracts the average data from the adder 426from the macroblock data MB(f) of the present frame. The adder 427produces output data which are inter-frame-encoded by the DCT circuit430, the quantizer 431, and the variable length coder 432. The encodeddata are supplied to the output encoder 433, which adds the decodinginformation EDa and inner and outer parity bits to the encoded data, andoutputs a B picture.

When all the macroblock data MB(f) stored in the frame memory 422 havebeen inter-frame-encoded in the manner described above, the frame imagedata stored in the frame memory 422 are read and supplied to the framememory 423, and stored as image data of a previous frame in the framememory 423. The frame memory 422 is now supplied with the image data ofthe next frame as the image data of the present frame.

The concept of the encoding process carried out by the image encoderwill be described below with reference to FIG. 2 of the accompanyingdrawings.

FIG. 2 shows the frame image data of successive frames that are to beencoded which are denoted by respective frame numbers F1˜F10. Thoseframe image data which are shown hatched are frame image data I1, I3,I5, I7, I9 as I pictures, and those frame image data which are shownblank are frame image data B2, B4, B6, B8, B10 as B pictures (or frameimage data P2, P4, P6, P8, P10 as P pictures). The frame image data I1,B2 of the frame numbers F1, F2 make up a GOP, the frame image data I3,B4 of the frame numbers F3, F4 make up a GOP, the frame image data I5,B6 of the frame numbers F5, F6 make up a GOP, the frame image data I7,B8 of the frame numbers F7, F8 make up a GOP, and the frame image dataI9, B10 of the frame numbers F9, F10 make up a GOP.

Of the frame image data shown in FIG. 2, the frame image data I1, I3,I5, I7, I9 of the frame numbers F1, F3, F5, F7, F9 are read from theframe memory 422 and supplied through the switch 428 to the DCT circuit430, the quantizer 431, and the variable length coder 432, whichintra-frame-encode the supplied frame image data.

For encoding image data of a B picture, as indicated by the arrows inFIG. 2, frame image data on both sides of frame image data to beencoded, i.e., frame image data of frames which precede and follow theframe image data to be encoded, are used to inter-frame-encode the imagedata. For example, the frame image data I1, I3 of the frames whichprecede and follow the frame image data of the frame number F2 are usedto encode the frame image data of the frame number F2, and the frameimage data I3, I5 of the frames which precede and follow the frame imagedata of the frame number F4 are used to encode the frame image data ofthe frame number F4.

For example, for encoding the frame image data B2 of the frame numberF2, the frame image data B2 are stored as the frame image data of thepresent frame in the frame memory 422 shown in FIG. 1. At this time, theframe memory 423 stores the frame image data I1 of the frame number F1as the frame image data of the preceding frame. When the frame imagedata B2 start being encoded, the frame image data I3 of the frame numberF3 are supplied as the frame image data of the following frame throughthe input terminal 400.

The motion detector 421 detects a motion with respect to the macroblockdata MB(f) of the frame image data B2 of the frame number F2 which areread from the frame memory 422 and the macroblock data MB(f-1) of theframe image data I1 of the frame number F1 which are read from the framememory 423, and, as a result, produces one set of motion vector data MV.The motion detector 421 detects a motion with respect to the macroblockdata MB(f) of the frame image data B2 of the frame number F2 which areread from the frame memory 422 and the macroblock data MB(f+1) of theframe image data I3 of the frame number F3 which are supplied from theinput terminal 400, and, as a result, produces one set of motion vectordata MV.

The motion compensator 424 extracts the macroblock data MB(f-1) of theframe image data I1 of the frame number F1 which are indicated by themotion vector data MV. The motion compensator 425 extracts themacroblock data MB(f+1) of the frame image data I3 of the frame numberF3 which are indicated by the motion vector data MV. The macroblock dataMB(f-1), MB(f+1) which are extracted respectively by the motioncompensators 424, 425 have their contents, i.e., their arrangement ofthe levels of pixel data in the macroblocks, closet to the macroblockdata MB(f) of the frame image data B2 of the frame number F2.

The adder 426 adds the macroblock data MB(f-1) of the frame image dataI1 of the frame number F1 from the motion compensator 424 and themacroblock data MB(f+1) of the frame image data I3 of the frame numberF3 from the motion compensator 425 and multiplies the sum by "1/2" withthe 1/2 multiplier therein, thereby producing average data representingthe average of the two macroblock data MB(f-1), MB(f+1). The averagedata are supplied from the adder 426 to the adder 427 through thesubtractive input terminal thereof.

The adder 427 is also supplied with the macroblock data MB(f) of theframe image data B2 of the frame number F2 through the additive inputterminal thereof. The adder 427 thus subtracts the average data from themacroblock data MB(f) of the frame image data B2 of the frame number F2,producing differential data. The produced differential data are suppliedthrough the switch 428 to the DCT circuit 430, the quantizer 431, andthe variable length coder 432, which encode the differential data. Theabove process is effected on all the macroblock data MB(f) of the frameimage data B2 of the frame number F2, thereby interframe-encoding theframe image data B2 of the frame number F2. The frame image data B4, B6,B8, F10 of the frame numbers F4, F6, F8, F10 are similarly inter-frameencoded.

The concept of a decoding process will be described below with referenceto FIG. 2. FIG. 2 shows the frame image data to be decoded of successiveimage frames which are denoted by respective frame numbers F1˜F10. Thoseframe image data which are shown hatched are frame image data as Ipictures, and those frame image data which are shown blank are frameimage data as B pictures (or frame image data as P pictures).

Of the frame image data shown in FIG. 2, the frame image data I1, I3,I5, I7, I9 of the frame numbers F1, F3, F5, F7, F9 are decoded by theimage decoder and then outputted as reproduced image data.

As indicated by the arrows in FIG. 2, frame image data as a B pictureare decoded using frame image data on both sides of the frame image datato be decoded, i.e., frame image data of frames which precede and followthe frame image data to be decoded. For example, the frame image dataI1, I3 of the frames which precede and follow the frame image data B2 ofthe frame number F2 are used to decode the frame image data B2 of theframe number F2.

For example, for decoding the frame image data B2 of the frame numberF2, the frame image data I1 of the frame number F1 as an I picture andthe frame image data I3 of the frame number F3 as an I picture are usedto decode the frame image data B2 of the frame number F2. The decodingprocess employs the motion vector data which have been produced by themotion detection with respect to the frame image data B2 of the framenumber F2 and the frame image data I1 of the frame number F1, and alsothe frame image data B2 of the frame number F2 and frame image data I3of the frame number F3.

The macroblock data indicated by the motion vector data are extractedfrom the frame image data of the frame number F1, and the macroblockdata indicated by the motion vector data are extracted from the frameimage data of the frame number F3. These macroblock data are added toeach other, and averaged to produce average data by being multiplied bythe coefficient "1/2". The differential data of the frame image data B2of the frame number F2 and the average data are added to each other,thereby restoring the macroblock data of the frame image data B2 of theframe number F2.

The above compression encoding process is employed when digital videodata are recorded on magnetic tapes, optical disks such as CD-ROMs, andhard disks. For compressing and encoding moving image data of a longperiod of time, such as movie image data and recording all thecompressed and encoded moving image data on such a storage medium, it isnecessary that the amount of all image data to be recorded which havebeen compressed and encoded be equal to or smaller than the remainingamount of data available after the decoding information EDa and theparity bits are removed from the amount of all data that can be recordedon the storage medium.

For example, CD-ROMs are mass-produced by a stamper as a master. Such astamper is manufactured by the following manufacturing steps:

1. A glass substrate is coated with a resist material, forming a resistfilm on the glass substrate.

2. Digital video data which have been compressed and encoded that arecarried by a laser beam emitted from a laser beam source are applied tothe resist film.

3. Only the area of the resist film to which the laser beam has beenapplied is removed by development.

4. A melted resin such as polycarbonate or the like is flowed onto theresist film on the glass substrate.

5. After the resin layer is hardened, it is peeled off the glasssubstrate.

6. The irregular surface of the resin layer is plated by electrolessplating, so that a plated layer is formed on the irregular surface ofthe resin layer.

7. The plated layer is then plated with a metal such as nickel or thelike, so that a metal plated layer is formed on the plated layer on theirregular surface of the resin layer.

8. The resin layer is then peeled off the plated layer on the irregularsurface of the resin layer.

The remaining plated layer after the resin layer is peeled off serves asthe stamper.

Unlike hard disks and magnetooptical disks, digital video data arecompressed, encoded, and recorded on optical disks such as CD-ROMs whenthe above stamper is manufactured. If the amount of all compressed andencoded image data to be recorded is smaller than the amount of allimage data that can be recorded on the glass substrate, then all thecompressed and encoded image data are recorded on the glass substrate,only leaving a blank area free of any recorded digital video data in therecordable area of the glass substrate. However, if the amount of allcompressed and encoded image data to be recorded is greater than theamount of all image data that can be recorded on the glass substrate,then some of all the compressed and encoded image data to be recordedare not recorded on the glass substrate.

Storage mediums such as magnetooptical disks, hard disks, or the likewhere data can be recorded repeatedly in the same storage area canremedy the above problem by recording the data again on the storagemedium though it results in an expenditure of additional time. However,storage mediums such as CD-ROMs which are mass-produced by one or morestampers cannot alleviate the above drawback unless a stamper orstampers are fabricated again, resulting in a much greater expenditureof time and expenses. Once CD-ROMs mass-produced by a stamper orstampers that are fabricated from a glass substrate which misses some ofall the compressed and encoded image data to be recorded are on themarket, the CD-ROM manufacturer has to collects those CDROMs from themarket.

According to one conventional solution, a single quantization step sizecapable of recording all image data to be recorded on a storage mediumis determined based on the amount of all image data to be recorded andthe storage capacity of the storage medium, and the data of thequantization step size are supplied to a quantizer when the image dataare recorded on the storage medium. Stated otherwise, the quantizationstep size in the quantizer 431 in the image encoder shown in FIG. 1 maybe set to a predetermined quantization step size. In this manner, allimage data to be recorded can reliably be recorded on a storage medium.

Moving image data vary at different degrees from frame to frame. Movingobjects in moving images have various complex moving patterns includingsimple translation, different moving speeds, different movingdirections, changes in moving directions per unit time, changes in theshape of moving objects, etc. If the moving pattern of a moving objectis not simple translation, then when macroblock data closest tomacroblock data in frame image data to be encoded of a present frame areextracted from frame image data of a preceding or following frame usingmotion vector data produced as a result of the detection of a motion bythe motion detector 21 shown in FIG. 1, a pattern of the levels of pixeldata in the extracted macroblock data of the preceding or followingframe is not greatly different from a pattern of the levels of pixeldata in the macroblock data of the present frame.

Therefore, when the amount of differential data produced by subtractingthe average data of the macroblock data of the preceding and followingframe from the macroblock data of the present frame is not greatlydifferent from the amount of the macroblock data of the present frame.Specifically, when frames of moving image data are observed, since themoving image data do not vary constantly from image to image, the amountof data produced in each macroblock, each frame, and hence each GOP isnot constant.

Therefore, the moving image data, the amount of which produced in eachmacroblock, each frame, and hence each GOP is not constant, are alwaysquantized at a constant quantization step size. When the amount ofdifferential data from the adder 427 shown in FIG. 1 is large, the DCTcircuit 430 produces many types of coefficient data, but suchcoefficient data are quantized roughly at the single quantization stepsize by the quantizer 431. Conversely, when the amount of differentialdata from the adder 427 shown in FIG. 1 is smaller, the DCT circuit 430produces fewer types of coefficient data, but such coefficient data arequantized finely at the single quantization step size by the quantizer431.

For example, it is assumed that when the amount of differential data islarge, "20" types of coefficient data are produced, and when the amountof differential data is smaller, "4" types of coefficient data areproduced, and that the quantization step size is "4". When the amount ofdifferential data is large, the coefficient data are quantized at thequantization step size of "4" even though there are "20" types ofcoefficient data. When the amount of differential data is smaller, thecoefficient data are quantized at the quantization step size of "4" eventhough there are only "4" types of coefficient data. Accordingly, whenthe amount of information is large, it is quantized roughly, and whenthe amount of information is smaller, it is quantized finely. Since theinformation cannot be quantized appropriately depending on the amountthereof, the quality of an image restored from an image which contains alarge amount of information, in particularly, is poor.

There has been a demand for a method of and a system for quantizingimage data appropriately depending on the amount of differential data,and recording all image data reliably on a storage medium.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a methodof and a system for encoding image information, and a method of and asystem for recording image information, to record all image datareliably on a storage medium without lowering the quality of a restoredimage.

According to the present invention, there is provided a method ofrecording image information on a recording medium, comprising the stepsof storing motion vector information produced by detecting a motion ofimage information outputted from a signal source, detecting an amount ofencoded image information, in a predetermined unit, produced by encodingthe image information outputted from the signal source using the motionvector information, assigning an amount of information in the amount ofinformation recordable on the recording medium to image information inthe predetermined unit based on the amount of encoded image informationin the predetermined unit, obtaining compression ratio informationrepresenting a compression ratio used when the image information isencoded, based on the assigned amount of information, encoding the imageinformation outputted from the signal source using the motion vectorinformation and the compression ratio information, and recording theimage information thus encoded on the recording medium.

According to the present invention, there is also provided a method ofencoding image information, comprising the steps of storing motionvector information produced by detecting a motion of image informationoutputted from a signal source, detecting an amount of encoded imageinformation, in a predetermined unit, produced by encoding the imageinformation outputted from the signal source using the motion vectorinformation, assigning an amount of information in the amount ofinformation usable on a recording medium to image information in thepredetermined unit based on the amount of encoded image information inthe predetermined unit, obtaining compression ratio informationrepresenting a compression ratio used when the image information isencoded, based on the assigned amount of information, and encoding theimage information outputted from the signal source using the motionvector information and the compression ratio information.

According to the present invention, there is further provided a systemfor recording image information on a recording medium, comprising firstmemory means for storing image information outputted from a signalsource, motion detecting means for effecting a motion detecting processon main image information from the signal source and auxiliary imageinformation from the first memory means to produce motion vectorinformation, vector information memory means for storing the motionvector information produced by the motion detecting means, encodingmeans for encoding the image information outputted from the signalsource, recording means for recording the image information encoded bythe encoding means on the recording medium, decoding means for decodingthe image information encoded by the encoding means, second memory meansfor storing the image information decoded by the decoding means, motioncompensating means for reading image information represented by themotion vector information produced by the motion detecting means, fromthe second memory means, first adding means for subtracting theauxiliary image information read by the motion compensating means fromthe main image information from the signal source, second adding meansfor adding the image information decoded by the decoding means and theauxiliary image information read by the motion compensating means, andcontrol means for detecting the amount of the image information encodedby the encoding means, obtaining compression ratio informationrepresentative of a compression ratio in the encoding means based on thedetected amount of the image information, supplying the compressionratio information to the encoding means to control the compression ratioin the encoding means, and controlling the first memory means, themotion detecting means, the vector information memory means, theencoding means, the recording means, the decoding means, the secondmemory means, the motion compensating means, the first adding means, andthe second adding means, the control means comprising means forcontrolling the motion detecting means to produce the motion vectorinformation, detecting the amount of the image information encoded bythe encoding means, and calculating compression ratios of all the imageinformation to be recorded, in a predetermined unit, based on thedetected amount of the image information and an amount of informationrecordable on the recording medium, in a preprocessing procedure forproducing the motion vector information and calculating the compressionratio in the encoding means, and means for supplying the motion vectorinformation read from the vector information memory means to the motioncompensating means to use the motion vector information in the motioncompensating means, and controlling the compression ratio in theencoding means, when the image information outputted from the signalsource is recorded on the recording medium by the recording means.

According to the present invention, there is also provided a system forrecording image information on a recording medium, comprising memorymeans for storing image information outputted from a signal source,motion detecting means for effecting a motion detecting process on mainimage information from the signal source and auxiliary image informationfrom the first memory means to produce motion vector information, vectorinformation memory means for storing the motion vector informationproduced by the motion detecting means, encoding means for encoding theimage information outputted from the signal source, recording means forrecording the image information encoded by the encoding means on therecording medium, decoding means for decoding the image informationencoded by the encoding means, supplying the decoded information to thememory means, and storing the decoded information in the memory means,motion compensating means for reading image information represented bythe motion vector information produced by the motion detecting means,from the memory means, first adding means for subtracting the auxiliaryimage information read by the motion compensating means from the mainimage information from the signal source, second adding means for addingthe image information decoded by the decoding means and the auxiliaryimage information read by the motion compensating means, and controlmeans for detecting the amount of the image information encoded by theencoding means, obtaining compression ratio information representativeof a compression ratio in the encoding means based on the detectedamount of the image information, supplying the compression ratioinformation to the encoding means to control the compression ratio inthe encoding means, and controlling the memory means, the motiondetecting means, the vector information memory means, the encodingmeans, the recording means, the decoding means, the motion compensatingmeans, the first adding means, and the second adding means, the controlmeans comprising means for controlling the motion detecting means toproduce the motion vector information, detecting the amount of the imageinformation encoded by the encoding means, and calculating compressionratios of all the image information to be recorded, in a predeterminedunit, based on the detected amount of the image information and anamount of information recordable on the recording medium, in apreprocessing procedure for producing the motion vector information andcalculating the compression ratio in the encoding means, and means forsupplying the motion vector information read from the vector informationmemory means to the motion compensating means to use the motion vectorinformation in the motion compensating means, and controlling thecompression ratio in the encoding means, when the image informationoutputted from the signal source is recorded on the recording medium bythe recording means.

According to the present invention, there is further provided a systemfor encoding image information, comprising motion detecting means fordetecting a motion of image information outputted from a signal sourceto produce motion vector information, memory means for storing themotion vector information produced by the motion detecting means,encoding means for encoding the image information outputted from thesignal source based on the motion vector information produced by themotion detecting means or the motion vector information stored in thememory means, and control means for controlling the motion detectingmeans, the memory means, and the encoding means, the control meanscomprising means for storing the motion vector information produced bythe motion detecting means in the memory means, determining an amount ofinformation in a predetermined unit of the encoded image informationfrom the encoding means, and determining compression ratio informationrepresenting a compression ratio in the encoding means, in thepredetermined unit with respect to all image information to be recorded,based on the determined amount of information and a usable amount ofinformation, and means for reading the motion vector information fromthe memory means and supplying the read motion vector information andthe compression ratio information to the encoding means.

Before image information from the signal source is recorded on therecording medium by the recording means, motion vector informationproduced by the motion detecting means is stored in the memory means,and the amount of information with respect to an predetermined unit ofencoded information from the encoding means is determined. Based on thedetermined amount of information and the amount of informationrecordable on the recording medium, compression ration informationindicative of a compression ratio in the encoding means in the recordingprocess is determined in the predetermined unit. When the imageinformation from the signal source is recorded on the recording mediumby the recording means, the motion vector information stored in thememory means is read, and the read motion vector information and thecompression ratio information are supplied to the encoding means.Therefore, in a preprocessing procedure prior to the recording process,it is possible to obtain the motion vector information and thecompression ratio information in the predetermined unit of all the imageinformation for recording all the image information from the signalsource on the recording medium. In the recording process, the imageinformation is encoded using the motion vector information and thecompression ratio information, and recorded on the recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a conventional image encoder;

FIG. 2 is a diagram illustrative of an encoding process carried out bythe image encoder shown in FIG. 1 and a decoding process carried out byan image decoder;

FIG. 3A is a view of a source image recording medium and a storagemedium;

FIG. 3B is a view showing an image of an (n-1)th frame, illustrative oftranslation of an object;

FIG. 3C is a view showing an image of an nth frame, illustrative oftranslation of an object;

FIG. 3D is a view showing an image of an (n-1)th frame, illustrative ofrandom movement of an object;

FIG. 3E is a view showing an image of an nth frame, illustrative ofrandom movement of an object;

FIG. 4A is a diagram illustrative of the concept of a fixed-rateencoding process;

FIG. 4B is a diagram illustrative of the concept of a variable-rateencoding process;

FIG. 4C is a diagram illustrative of a comparison between the fixed andvariable rate encoding processes;

FIG. 5 is a block diagram of an image information recording apparatus,showing a conceptual arrangement of a first embodiment of the presentinvention;

FIG. 6 is a block diagram of a digital video data recording systemaccording to the first embodiment of the present invention;

FIGS. 7A through 7C are diagrams of table data stored in respectivetables in a table area 64b of a RAM in the digital video data recordingsystem;

FIG. 7D is a diagram showing motion vector data recorded on a hard disk;

FIGS. 8A and 8B show a menu image and a material data information image,respectively, which are displayed on the display panel of the LCD 60ashown in FIG. 6.

FIG. 9 is a flowchart of a main routine of control operation of thedigital video data recording system shown in FIG. 6;

FIG. 10 is a flowchart of control operation of the digital video datarecording system according to a material data entering routine in themain routine shown in FIG. 9;

FIGS. 11 and 12 are a flowchart of control operation of the digitalvideo data recording system according to a material data recordingroutine in the main routine shown in FIG. 9;

FIG. 13 is a block diagram of a video encoder in the digital video datarecording system shown in FIG. 6;

FIG. 14 is a block diagram of each of motion detectors in the videoencoder shown in FIG. 13;

FIGS. 15A and 15B are diagrams illustrative of an encoding process ofencoding image data outputted from a selector in the video encoder shownin FIG. 13;

FIG. 15C is a diagram illustrative of a process of decoding image dataencoded by the video encoder shown in FIG. 13;

FIG. 16 is a block diagram of an image information recording apparatus,showing a conceptual arrangement of a second embodiment of the presentinvention;

FIG. 17 is a block diagram of a digital video data recording systemaccording to the second embodiment of the present invention;

FIG. 18 is a block diagram of a digital video data recording systemaccording to a third embodiment of the present invention;

FIG. 19 is a diagram showing a recording table used in the digital videodata recording system shown in FIG. 18;

FIGS. 20 and 21 are flowcharts of an operation sequence of the digitalvideo data recording system shown in FIG. 18; and

FIG. 22 is a block diagram of a digital video data recording systemaccording to a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A. Principles of theInvention

FIGS. 3A through 3E and 4A through 4C show the principles of the presentinvention.

As shown in FIG. 3A, a source image recording medium comprises amagnetic tape, for example, and a storage medium comprises an opticaldisk, for example, and it is assumed that source image data recorded onthe magnetic tape are recorded on the optical disk. It is necessary thatthe source image data which have been recorded on the magnetic tape fora recording time T be fully recorded on the optical disk which has astorage capacity S. If the optical disk comprises a CD-ROM or the likewhich is manufactured by a stamper, then the process of recording thesource image data on the optical disk is more strictly a process ofrecording the source image data on a glass substrate for fabricating astamper which is used to manufacture the optical disk.

FIGS. 3B and 3C and FIGS. 3D and 3E show frame image data of (n-1)th andnth frames which are extracted from a series of frame image data thatare produced when a running chick is shot by a video camera which isfixed. FIG. 3B shows preceding frame image data V(n-1) of an (n-1)thframe, and FIG. 3C shows present frame image data V(n) of an nth framewhich follows in time the preceding frame image data V(n-1) shown inFIG. 3B. FIG. 3D shows preceding frame image data V(n-1) of an (n-1)thframe, and FIG. 3E shows present frame image data V(n) of an nth framewhich follows in time the preceding frame image data V(n) shown in FIG.3D.

For illustrative purpose, it is assumed that the size of one macroblock,described above, is large enough to surround chicks Pi(n-1) and Pi(n)shown in FIGS. 3B through 3E.

The chick Pi(n-1) which is a moving object in the image represented bythe preceding frame image data V(n-1) is positioned as shown in FIG. 3B.In the image represented by the present frame image data V(n) whichfollows the preceding frame image data V(n-1), the chick Pi ispositioned at a right-hand end as shown in FIG. 3C. This is because thechick has run between the two frames within a range that can be shot bythe video camera.

The above translation of the chick will be described below in terms ofmacroblock data. In the preceding frame image data V(n-1), macroblockdata B(n-1) are spaced a distance ml from the left-hand end of the imageas shown in FIG. 3B. In the present frame image data V(n) which followsthe preceding frame image data V(n-1), macroblock data B(n) are spaced adistance m2 from the left-hand end of the image as shown in FIG. 3C.These macroblock data B(n-1), B(n) are identical to each other.

For motion detection, an agreement between the macroblock data B(n) ofthe present frame and all macroblock data in a search area which isestablished in the preceding frame image data V(n-1) is detected, andmotion vector data are produced based on the macroblock data of thepreceding frame which provide the best agreement. For motioncompensation, the macroblock data B(n-1) represented by the motionvector data are extracted from preceding frame image data V(n-1), andthe extracted macroblock data B(n-1) of the preceding frame aresubtracted from the macroblock data B(n) of the present frame.

When the chick is translated as shown in FIGS. 3B and 3C, therefore, apattern of the levels of pixel data in the macroblock data B(n-1) of thepreceding frame and a pattern of the levels of pixel data in themacroblock data B(n) of the present frame are identical to each other,and any differential data produced when the extracted macroblock dataB(n-1) are subtracted from the macroblock data B(n) are "0".Consequently, the amount of differential data is minimum when an objectis translated.

In FIGS. 3D and 3E, the chick Pi(n-1) in the image represented by thepreceding frame image data V(n-1) and the chick Pi(n) in the imagerepresented by the present frame image data V(n) face in differentdirections, and the chick is not completely translated in an interval oftime between these two frames. In this case, there is almost nosimilarity between a pattern of the levels of pixel data in themacroblock data B(n-1) of the preceding frame and a pattern of thelevels of pixel data in the macroblock data B(n) of the present frame,and any differential data produced when the extracted macroblock dataB(n-1) are subtracted from the macroblock data B(n) are large.Consequently, the amount of differential data is large when an objectmakes a complex motion.

Image data characterized by a smaller amount of differential data willhereinafter referred to as an "image of good encoding efficiency", andimage data characterized by a larger amount of differential data willhereinafter referred to as an "image of poor encoding efficiency".

Images include images of good encoding efficiency and images of poorencoding efficiency. Encoding processes include a fixed-rate encodingprocess and a variable-rate encoding process in which the quantizationstep size is varied depending on the complexity of image data to beencoded. The fixed-rate encoding process, the variable-rate encodingprocess, and the difference between the fixed- and variable-rateencoding processes will be described below with reference to FIGS. 4Athrough 4C.

FIG. 4A is illustrative of the fixed-rate encoding process. In FIG. 4A,the vertical axis represents the amount of generated data, thehorizontal axis represents time in terms of seconds (t), S indicates thestorage capacity of the storage medium shown in FIG. 3A, T indicates aperiod of time for which source image data are recorded on the sourceimage recording medium, and ts indicates the duration of time of anyoptional scene, e.g., a GOP.

In the fixed-rate encoding process, since a quantizer has a constantquantization step size, the amount of encoded data is of a constantvalue x(i) as shown in FIG. 4A regardless of whether image data to beencoded represents an image of good encoding efficiency or an image ofpoor encoding efficiency.

FIG. 4B is illustrative of the variable-rate encoding process. In FIG.4B, the vertical axis represents the amount (d) of generated data, thehorizontal axis represents time in terms of seconds (t), T indicates aperiod of time for which source image data are recorded on the sourceimage recording medium, ts indicates the duration of time of anyoptional scene, e.g., a GOP, and d(i-2), d(i-1), . . . , d(i+3) indicatethe respective amounts of generated data in respective scenes, with theprogressively greater values in parentheses signifying more subsequentscenes.

In the variable-rate encoding process, a quantizer has a variablequantization step size which is varied depending on the complexity ofimage data to be encoded. If the image data to be encoded represents animage of good encoding efficiency, then the variable quantization stepsize of the quantizer is reduced. If the image data to be encodedrepresents an image of poor encoding efficiency, then the variablequantization step size of the quantizer is increased. Therefore, asshown in FIG. 4B, the amount of encoded data varies from scene to scene.

FIG. 4C illustrates the difference between the fixed- and variable-rateencoding processes. In FIG. 4C, the vertical axis represents the bitrate, and the horizontal axis represents time in terms of seconds (t).The straight-line curve shows the bit rate when image data are encodedby the fixed-rate encoding process. The broken-line curve shows the bitrate when image data are encoded by the variable-rate encoding process.In FIG. 4C, Sa represents an image of good encoding efficiency, and Sbrepresents an image of poor encoding efficiency.

As shown in FIG. 4C, when the image data of the image Sa of goodencoding efficiency are encoded by the variable-rate encoding process,the bit rate is lower by a stippled area than when they are encoded bythe fixed-rate encoding process. Conversely, when the image data of theimage Sa of good encoding efficiency are encoded by the fixed-rateencoding process, useless information is created. Stated otherwise,inasmuch as a small amount of differential data is quantized at a largequantization step size, the bit rate of the quantized image data isunduly increased.

When the image data of the image Sb of poor encoding efficiency areencoded by the variable-rate encoding process, the bit rate is higher bya hatched area than when they are encoded by the fixed-rate encodingprocess. Conversely, when the image data of the image Sb of poorencoding efficiency are encoded by the fixed-rate encoding process, alack of information occurs. Stated otherwise, inasmuch as a large amountof differential data is quantized at a small quantization step size, thebit rate of the quantized image data is unduly reduced.

It follows from the above analysis of the fixed- and variable-rateencoding processes that it is necessary to employ the variable-rateencoding process in order to encode image data. However, if the sourceimage data which have been recorded on the source image recording mediumfor the recording time T are to be fully recorded on the storage mediumhaving the storage capacity S, then different preprocessing proceduresare required by the fixed-rate encoding process and the variable-rateencoding process, respectively.

For encoding image data according to the fixed rate encoding process, afixed quantization step size capable of fully recording the source imagedata which have been recorded on the source image recording medium forthe recording time T on the storage medium having the storage capacity Sis determined based on the recording time T and the storage capacity S,and data indicative of the fixed quantization step size are given to aquantizer to record the image data.

For encoding image data according to the variable-rate encoding process,the quantization step size used by a quantizer is variable depending onthe amount of differential data. Before source image data are actuallyrecorded on the storage medium, it is necessary to encode the sourceimage data, detect the amounts of encoded data of respective scenes, anddivide and assign the storage capacity of the storage medium to theamounts of encoded data of respective scenes in such a manner that thesum of the amounts of encoded data of respective scenes is equal to orsmaller than the storage capacity of the storage medium.

It can be understood from the above explanation of the fixed- andvariable-rate encoding processes that the quality of an image producedwhen image data encoded by the fixed-rate encoding process are decodedis lower than the quality of an image produced when image data encodedby the variable-rate encoding process are decoded, but the fixed rateencoding process is advantageous in that any preprocessing procedurerequired by the fixed-rate encoding process may be simple calculationsonly. While the quality of an image produced when image data encoded bythe variable-rate encoding process are decoded is much higher than thequality of an image produced when image data encoded by the fixed-rateencoding process are decoded, the variable-rate encoding process isdisadvantageous in that it requires a preprocessing sequence of encodingimage data and detecting the amounts of encoded data of all image datato be recorded.

Because it is a vital requirement to increase the quality of imagesproduced when encoded image data are decoded, however, the variable-rateencoding process as a whole is more advantageous than the fixed-raterecording process insofar as the preprocessing procedure of thevariable-rate encoding process is simplified as much as possible.

B. Concept of 1st Embodiment

FIG. 5 illustrates in block form an image information recordingapparatus, showing a conceptual arrangement of a first embodiment of thepresent invention.

Structure:

As shown in FIG. 5, the image information recording apparatus comprisesa signal source 1 for outputting image information to be recorded, afirst memory 2 for storing the image information supplied from thesignal source 1, a motion detector 3 for detecting a motion based on theimage information supplied from the signal source 1 and the imageinformation supplied from the first memory 2, switches 4, 6, 5 forselectively electrically connecting the signal source 1 and the motiondetector 3, the first memory 2 and the motion detector 3, and the motiondetector 3 and a motion compensator 15, an external memory 8 for storingmotion vector data supplied from the motion detector 3, a delay unit 9for delaying the image information supplied from the signal source 1, anadder 10 for subtracting motion-compensated image information suppliedfrom the motion compensator from the delayed image information suppliedfrom the delay unit 9, an encoder 11 for encoding output data from theadder 10, a decoder 12 for decoding the encoded output data suppliedfrom the encoder 11, an adder 13 for adding decoded output data suppliedfrom the decoder 12 and the image information which has beenmotion-compensated by the motion compensator 15 and delayed by a delayunit 16, a second memory 14 for storing output data from the adder 13,the motion compensator 15 for extracting image information representedby the motion vector data from the external memory 8 from the imageinformation stored in the second memory 14, the delay unit 16 fordelaying the image information supplied from the motion compensator 15,a controller 7 for controlling the above components and determining acompression ratio in the encoder 11 depending on the complexity ofimages, and a recorder 17 for recording the encoded output data suppliedfrom the encoder 11.

Before image information from the signal source 1 is recorded on arecording medium by the recorder 17, the image information recordingapparatus effects a preprocessing procedure of storing motion vectordata produced by the motion detector 3 in the external memory 8 anddetermining a compression ratio for one or more images. The imageinformation recording apparatus uses the motion vector data stored inthe external memory 8 when the image information from the signal source1 is recorded on the recording medium by the recorder 17.

Specifically, the image information recording apparatus first effectsthe preprocessing procedure. In the preprocessing procedure, the motiondetector 3 determines motion vector data, which are stored in theexternal memory 8. The controller 7 determines a compression ratio forone or more images. Thereafter, the image information recordingapparatus effects a recording process. In the recording process, imageinformation represented by the motion vector data read from the externalmemory 8 is read from the second memory 14 by the motion compensator 15,and subtracted from image information supplied from the delay unit 9 bythe adder 10. Differential data outputted from the adder 10 are encodedby the encoder 11 at the compression ratio determined in thepreprocessing procedure, and encoded output data from the encoder 11 arerecorded on the recording medium by the recorder 11.

In summary, in the case where the variable-rate encoding process isemployed in the image information recording apparatus, motion vectordata are determined in the preprocessing procedure and stored in theexternal memory 8, and when the image information from the signal source1 is to be recorded on the recording medium by the recorder 17, themotion vector data stored in the external memory 8 are used, andcompression ratio information determined in the preprocessing procedureis also used. Thus, the image information recording apparatus is notrequired to have the motion detector 3 carry out a motion detectingprocess, and is capable of fully recording the image information to berecorded, on the recording medium.

Operation in Preprocessing Procedure:

Operation of the image information recording apparatus in thepreprocessing procedure will be described below.

The switches 4, 5, 6 are turned on by switch control signals from thecontroller 7. The motion detector 3 and the signal source 1, the motiondetector 3 and the first memory 2, and the motion detector 3 and theexternal memory 8 are electrically connected when the respectiveswitches 4, 6, 5 are turned on.

The signal source 1 starts to output image information under the controlof the controller 7. The image information outputted from the signalsource 1 is supplied to and stored in the first memory 2. The imageinformation outputted from the signal source 1 is also supplied to themotion detector 3 as indicated by the arrow Px1 in FIG. 5. At the sametime, the image information stored in the first memory 2 is readtherefrom and supplied to the motion detector 3 as indicated by thearrow Px2 under the control of the controller 7. The motion detector 3effects a motion detecting process on the image information from thesignal source 1 and the image information from the first memory 2, andproduces motion vector data based on the result of the motion detectingprocess. The motion vector data generated by the motion detector 3 aresupplied to the external memory 8 as indicated by the arrow Px3. Theexternal memory 8 stores the motion vector data supplied from the motiondetector 3 according to a control signal supplied from the controller 7.The controller 7 determines a compression ratio for one or more images.The above preprocessing procedure is carried out with respect to allimage data to be recorded.

Operation in Recording Process:

Operation of the image information recording apparatus in the recordingprocess will be described below.

The switches 4, 5, 6 are turned off by switch control signals from thecontroller 7. The motion detector 3 and the signal source 1, the motiondetector 3 and the first memory 2, and the motion detector 3 and theexternal memory 8 are electrically disconnected when the respectiveswitches 4, 6, 5 are turned off.

The signal source 1 starts to output image information under the controlof the controller 7. The image information outputted from the signalsource 1 is supplied to the delay unit 9 as indicated by the arrow Py1.The image information is then delayed by the delay unit 9 for a periodof time which is required by a motion compensating process in the motioncompensator 15, and then supplied to the adder 10. The image informationwhich is supplied to the adder 10 for the first time is outputted as itis from the adder 10 because no image information is supplied from themotion compensator 15 to the adder 10. The image information outputtedfrom the adder 10 is supplied to the encoder 11 as indicated by thearrow Py2, and encoded by the encoder 11. The encoded image informationis supplied to the decoder 12 as indicated by the arrow Py3, and decodedback to the original image information by the decoder 12. The decodedimage information is supplied to the adder 13.

The image information which is supplied to the adder 13 for the firsttime is outputted as it is from the adder 13 because no imageinformation is supplied from the motion compensator 15 through the delayunit 16 to the adder 13. The image information outputted from the adder13 is supplied to the second memory 14, and stored in the second memory14 according to a control signal from the controller 7.

The image information successively outputted from the signal source 1 isdelayed for the above delay time by the delay unit 9, and then suppliedto the adder 10 as indicated by the arrow Py1. At the same time, themotion vector data stored in the external memory 8 are read therefromaccording to a control signal that is supplied from the controller 7 tothe external memory 8. The motion vector data read from the externalmemory 8 are supplied to the motion compensator 15 as indicated by thearrow Py4. The motion compensator 15 reads image information representedby the motion vector data supplied from the external memory 8 from thesecond memory 14 as indicated by the arrow Py5. The image informationread from the second memory 14 is supplied to the adder 10 as indicatedby the arrow Py6.

The adder 10 subtracts the image information read from the second memory14 by the motion compensator 15 from the image information supplied fromthe signal source 1 through the delay unit 9. Differential dataoutputted as a resultant sum from the adder 10 are supplied to theencoder 11 as indicated by the arrow Py2, and encoded by the encoder 11based on the compression ratio information which has been determined inthe preprocessing procedure. The encoded image information from theencoder 11 is then supplied to the recorder 17 as indicated by the arrowPy7, and recorded on the recording medium by the recorder 17.

The image information read by the motion compensator 15 is also suppliedthrough the delay unit 16 to the adder 13 as indicated by the arrow Py8.The adder 13 adds the image information from the decoder 12 and theimage information from the delay unit 16. Sum output data from the adder13 are supplied to the second memory 14 as indicated by the arrow Py9,and stored in the second memory 14. The above recording process iscarried out with respect to all image data to be recorded.

Advantages of the Concept of 1st Embodiment:

As can be seen from the above explanation of the concept of the firstembodiment, the image information recording apparatus shown in FIG. 5carries out the preprocessing procedure by determining motion vectordata, and storing the motion vector data in the external memory 8, andcarries out the recording process by effecting a motion compensatingprocess using the motion vector data stored in the external memory 8without effecting a motion detecting process in the motion detector 3,and subtracting image information produced by the motion compensationfrom image information to be encoded. Therefore, in the case where theencoder 11 employs the variable-rate encoding process, the recordingprocess can reliably be carried out. Since it is not necessary in therecording process to effect a motion detecting process in the motiondetector 3 which is of a large circuit scale, the consumption ofelectric energy by the image information recording apparatus is greatlyreduced. Accordingly, the image information recording apparatus offersoutstanding advantages in that it employs the variable-rate encodingprocess for improved image quality and simplifies the overall processfor largely reducing the consumption of electric energy.

Specific details of the first embodiment will be described below withreference to FIG. 6. In FIG. 6, a reproducer 52 corresponds to thesignal source 1 shown in FIG. 5, a system controller 59 to thecontroller 7 shown in FIG. 5, an external memory 51 to the externalmemory 8 shown in FIG. 5, a master generator 58 to the recorder 17 shownin FIG. 5, and various circuits in a video encoder 55 to the remainingcomponents shown in FIG. 5.

C. Structure and Operation of Digital Video Data Recording System

FIG. 6 shows in block form a digital video data recording systemaccording to the first embodiment of the present invention. Structure:

As shown in FIG. 6, the digital video data recording system comprises areference clock generator 50 having a quartz crystal oscillator, forexample, an external memory 51 such as a hard disk drive or the like, areproducer 52 such as a digital VTR or the like, a delay unit 53 fordelaying video data from the reproducer 52 for a period of time which isrequired by an encoding process in an audio encoder 56, a video encoder55 for encoding the video data delayed by the delay unit 53, a delayunit 54 for delaying audio data from the reproducer 52 for a period oftime which is required by an encoding process in the video encoder 55,the audio encoder 56 for encoding the audio data delayed by the delayunit 54, an interface 57 for transmitting the encoded video data fromthe video encoder 55 and the encoded audio data from the audio encoder56 to a master generator 58, a system controller 59 for controlling theabove components, and a console 60 for giving instructions to the systemcontroller 59.

The master generator 58 may comprise any one of various systemsdescribed below. If a disk to be manufactured as a final product is aread-only disk such as a CD-ROM or the like, then one of at least twosystems may be employed for manufacturing the disk.

A first system is designed to manufacture a disk having two recordinglayers on one or both sides thereof. The first system comprises a devicefor exposing a resist layer on a glass substrate to a laser beam emittedfrom a semiconductor laser and modulated by recording data, a device fordeveloping the exposed glass substrate, a device for flowing a meltedresin such as polycarbonate or the like onto the glass substrate to forma first polycarbonate layer, a device for electrolessly plating thefirst polycarbonate layer which is peeled off the glass substrate afterthe first polycarbonate layer is hardened, plating the plated layer onthe first polycarbonate layer with a metal such as nickel, forminggrooves in a second polycarbonate layer, as melted, with a stamper whichis produced by peeling off the first polycarbonate layer, plating thesecond polycarbonate layer, flowing melted polycarbonate onto the platedlayer on the second polycarbonate layer or a surface of the secondpolycarbonate layer opposite to the plated layer to form a thirdpolycarbonate layer thereon, forming grooves in the third polycarbonatelayer with a stamper manufactured in the same manner as described aboveand carrying other video data recorded thereon, plating the thirdpolycarbonate layer, and flowing a resin such as polycarbonate or thelie onto the plated layer to provide a protective layer.

A second system is designed to manufacture a disk having two recordinglayers on one or both sides thereof. The second system comprises adevice for forming a resist layer on a disk of a resin such aspolycarbonate or the like, a device for exposing the resist layer to alaser beam emitted from a semiconductor laser and modulated by recordingdata, a device for developing the exposed resin disk, a device forplating the developed resin disk, a device for flowing a melted resinsuch as polycarbonate or the like onto the plated layer, a device forforming a resist layer on the polycarbonate layer or a surface oppositethereto, exposing the resist layer to a laser beam emitted from thesemiconductor laser and modulated by recording data, a device fordeveloping the exposed layer, a device for plating the developed layer,a device for flowing a melted resin such as polycarbonate or the likeonto the plated layer to provide a protective film.

For an optical disk such as a magnetooptical disk or a phase-changemedium, the master generator 58 serves as a drive capable of recordinginformation on and reproducing information from a disk which has asingle recording layer on one side thereof, a disk which has a singlerecording layer on each of two sides thereof, a disk which has tworecording layers on one side thereof, and a disk which has two recordinglayers on each of two sides thereof.

For recording information on and reproducing information from a diskhaving two recording layers, it is necessary to employ an optimumcombination of processes of employing two recording layers of differenttransmittances, detecting a light beam reflected in focus among lightbeams reflected from the two recording layers, causing an emitted layerbeam to be focused at different points on the two recording layers,varying the wavelength of an emitted layer beam with a wave plate, andemploying reverse logic schemes on the two recording layers.

The console 60 has a group of keys for supplying various commands to thesystem controller 59 and also an LCD (Liquid Crystal Display) 60a.

The internal structure of the system controller 59 will be describedbelow.

As shown in FIG. 6, the system controller 59 has a CPU 61 to which a busassembly 62 comprising address, data, and control buses is connected.The system controller 59 also has a ROM 63 which stores program data,parameter data, etc., a RAM 64 including a work area 64A and a tablearea 64b, and an input/output port 65 for transmitting and receivinginformation to the above components of the digital video data recordingsystem, all connected to the bus assembly 62.

When the digital video data recording system is turned on, the CPU 61performs various functions which are indicated in an area surrounded bythe broken lines in the system controller 59.

The functions performed by the CPU 61 will be described below.

A console controller 66 has a function to analyze control informationrepresented by a control key (not shown) of the console 60 when thecontrol key is pressed, a function to display a menu image (describedlater on) on the display panel of the LCD 60a, and a function to convertinformation to be displayed on the display panel of the LCD 60a intocharacter data.

A timing controller 67 has a function to give various timing signals tothe external memory 51, the reproducer 52, the delay units 53, 54, thevideo encoder 55, the audio encoder 56, the interface 57, and the mastergenerator 58, based on a reference clock signal from the reference clockgenerator 50.

An internal memory controller 68 has a function to supply a read controlsignal to the ROM 63 for reading data stored in the ROM 63, and afunction to supply a read/write control signal to the RAM 64 for writingdata in the RAM 64 and reading data from the RAM 64.

A reproducer controller 69 has a function to supply a control signal tothe reproducer 52 through the input/output port 65 for controllingoperation of the reproducer 52.

A GOP bit number detector 70 has a function to detect the number of bitsof each encoded GOP supplied from the video encoder 55 through theinput/output port 65.

A table controller 71 has a function to control the registration of thenumber of bits of each encoded GOP, detected by the GOP bit numberdetector 70, in a table stored in the table area 64b of the RAM 64, andthe readout of the data registered in the table.

A GOP ratio calculator 72 has a function to calculate a ratio(hereinafter referred to as a "GOP ratio") of the number of bits of eachencoded GOP to the number of bits recordable on the recording medium,based on the number of bits of each encoded GOP stored in the table.

A quantization controller 73 has a function to determine, with respectto each GOP, quantization step size data for assigning a recordablestorage capacity of the recording medium to each GOP based on the GOPratio calculated by the GOP ratio calculator 72, and supply thequantization step size data determined with respect to each GOP to thevideo encoder 55.

An encoder controller 74 has a function to control encoding processes inthe video encoder 55 and the audio encoder 56.

An external memory controller 75 has a function to supply a controlsignal through the input/output port 65 to the external memory 51 forcontrolling the external memory 51.

More specific functions other than the functions described above will bedescribed below with respect to operation of the digital video datarecording system. Operation:

Operation of the digital video data recording system shown in FIG. 6will be described below.

First, the digital video data recording system operates to determinemotion vector data with respect to all video data to be recorded andalso quantization step size data, and does not carry out a recordingprocess.

The reproducer 52 is controlled by the system controller 59 to startreproducing video and audio data. The reproduced video data from thereproducer 52 are supplied through the delay unit 53 to the videoencoder 55, which effects a motion detecting process and an encodingprocess on the video data. The audio data from the reproducer 52 aresupplied through the delay unit 54 to the audio encoder 56, whicheffects an encoding process on the audio data.

When the video encoder 55 starts the motion detecting process, the videoencoder 55 starts to produce successive motion vector data. The motionvector data produced by the video encoder 55 are supplied to the systemcontroller 59, which supplies the motion vector data through theinput/output port 65 to the external memory 51 and stores the motionvector data in the external memory 51. The video encoder 55 also effectsthe encoding process on the video data. The video data encoded by thevideo encoder 55 are supplied to the system controller 59, which detectsthe number of bits of each encoded GOP, determines a GOP ratio based onthe detected number of bits of each encoded GOP, and determinesquantization step size data based on the GOP ratio. The above process iscontinuously carried out with respect to all the video data to berecorded.

Then, the digital video data recording system starts to record the videodata. The reproducer 52 is controlled by the system controller 59 tostart reproducing video and audio data. The reproduced video data fromthe reproducer 52 are supplied through the delay unit 53 to the videoencoder 55, which effects an encoding process on the video data. Theaudio data from the reproducer 52 are supplied through the delay unit 54to the audio encoder 56, which effects an encoding process on the audiodata.

When the video encoder 55 starts the encoding process, the systemcontroller 59 reads the motion vector data from the external memory 51,and supplies the motion vector data to the video encoder 55. The systemcontroller 59 also supplies the quantization step size data to the videoencoder 55. The video encoder 55 effects a motion compensating processon the video data based on the motion vector data, and also effects aquantizing process on the video data based on the quantization step sizedata.

The video encoder 55 mixes the encoded video data with the audio datafrom the audio encoder 56. Output data from the video encoder 55 aresupplied through the interface 57 to the master generator 58, whichrecords the data on a master with a laser beam or the like. The aboverecording process is carried out with respect to all video data to berecorded.

D. Table Data in Table Area 64b

FIGS. 7A through 7C show table data stored in respective tables in thetable area 64b of the RAM 64 shown in FIG. 6. FIG. 7D shows motionvector data recorded on a hard disk.

FIG. 7A shows table data stored in a time code table in the table area64b of the RAM 64. The time code table stores material ID datarepresenting a material recorded in the recording medium loaded in thereproducer 52, start time code data recorded at the start position ofthe recording medium, and end time code data recorded at the endposition of the recording medium. The characters "hh:mm:ss:ff" in thecolumns of the start time code data and the end time code data representhour (hh), minute (mm), second (s), and frame (ff). The time code tableis referred to by the reproducer controller 69 shown in FIG. 6.

FIG. 7B shows table data stored in a GOP table in the table area 64b ofthe RAM 64. The GOP table stores material ID data representing amaterial recorded in the recording medium loaded in the reproducer 52,GOP number data representing the numbers or positions of the GOPs fromthe start of the recording medium, bit number data representing thenumbers of bits of the GOPs, GOP ratio data, assigned bit number data,and quantization step size data QST.

The bit number data represent the number of bits of each GOP detected bythe GOP bit number detector 70 shown in FIG. 6. The GOP ratio datarepresent a value produced when the bit number data of each GOP aredivided by the total storage capacity of the recording medium. Theassigned bit number data represent the number of bits to be assigned toa GOP by the quantization controller 73 based on the GOP ratio and thetotal storage capacity of the recording medium. The quantization stepsize data QST comprise data to be determined by the quantizationcontroller 73, and represent a quantization step size for making thenumber of bits of encoded data produced after an output encodingprocess, equal to the number of bits represented by the assigned bitnumber data.

An example will be described on the assumption that the recording mediumin the master generator 58 has a total storage capacity of 800 hundredmillion bits, one material is composed of two GOPs, the number of bitsof a GOP having a GOP number "01" encoded in the preprocessing procedureis 2400 hundred millions, and the number of bits of a GOP having a GOPnumber "02" encoded in the preprocessing procedure is 800 hundredmillions.

The sum of the number of bits of an encoded GOP having a GOP number "01"and the number of bits of an encoded GOP having a GOP number "02" is3200 hundred millions. Since the recording medium has a total storagecapacity of 800 hundred million bits, the data of 3200 hundred millionbits cannot be recorded on the recording medium. The GOP ratio data ofthe GOP number "01" is 2400 hundred millions/800 hundred millions, i.e.,3:1, and the GOP ratio data of the GOP number "02" is 800 hundredmillions/800 hundred millions, i.e., 1:1. Therefore, the total storagecapacity of 800 hundred million bits of the recording medium may bedivided such that the ratio of the number of bits assigned to the GOP ofthe GOP number "01" to the number of bits assigned to the GOP of the GOPnumber "02" is 3:1. As a result, 600 hundred million bits out of thetotal storage capacity are assigned to the GOP of the GOP number "01",and 200 hundred million bits out of the total storage capacity areassigned to the GOP of the GOP number "02".

The quantization step size data QST for the GOP of the GOP number "01"is set to a value for changing the total number of bits of the imagedata of the GOP after the output encoding process from original 2400hundred millions to 600 hundred millions. The quantization step sizedata QST for the GOP of the GOP number "02" is set to a value forchanging the total number of bits of the image data of the GOP after theoutput encoding process from original 800 hundred millions to 200hundred millions.

FIG. 7C shows table data stored in a hard disk table in the table area64b of the RAM 64, which is used if the external memory 51 shown in FIG.6 comprises a hard disk drive. The hard disk table stores material IDdata representing a material recorded in the recording medium loaded inthe reproducer 52, track/sector number data representing addresses onthe hard disk, and data length data (unit:byte) representing the lengthsof data from the positions of the track/sector number data.

FIG. 7D shows motion vector data recorded on the hard disk. As shown inFIG. 7D, motion vector data produced with respect to video data of onematerial are recorded on the hard disk in the following format: Whenvideo data are recorded, the material ID data are first recorded, andthen GOP number data are recorded, which are followed by successivemotion vector data determined with respect to image data correspondingto the GOP number data.

E. Images Displayed on LCD 60a

FIGS. 8A and 8B show a menu image and a material data information image,respectively, which are displayed on the display panel of the LCD 60ashown in FIG. 6.

As shown in FIG. 8A, the menu image displayed on the display panel ofthe LCD 60a contains two selectable items of entering material data andrecording material data. One of the items can be selected by a cursorkey (not shown) of the console 60, and the selected item can be executedwhen an enter key (not shown) of the console 60 is pressed. The item ofentering material data is a process of entering a position of a materialto be recorded, on the recording medium in the reproducer 52, and theitem of recording material data is a process of recording the material,specified by the above item of entering material data, on the recordingmedium in the reproducer 52 on the recording medium in the mastergenerator 59.

If the item of entering material data on the display panel is selected,then a material data information image shown in FIG. 8B is displayed onthe display panel of the LCD 60a. As shown in FIG. 8B, the material datainformation image contains a material ID, a recording start time code,and a recording end time code. When the user enters numerical valuesthrough the console 60 while the material data information image isbeing displayed on the display panel of the LCD 60a, the enterednumerical values are displayed as the recording start time code or therecording end time code on the display panel of the LCD 60a. When theuser thereafter presses the enter key, the material automatically startsto be recorded under the control of the system controller 59.

F. Main Routine of Control Operation of the Digital Video Data RecordingSystem

FIG. 9 shows a main routine of control operation of the digital videodata recording system shown in FIG. 6. The control operation is mainlycarried out by the functions which are performed by the CPU 61 shown inFIG. 6.

In a step S1 shown in FIG. 9, the internal memory controller 68 readsmenu image data from the ROM 63 under the control of the consolecontroller 66 shown in FIG. 6. The menu image data read from the ROM 63are supplied through the input/output port 65 to the console 60, anddisplayed as the menu image on the display panel of the LCD 60a. Then,control proceeds to a step S2.

In the step S2, the console controller 66 decides whether the user haspressed the enter key (not shown) of the console 60 or not. If the userhas pressed the enter key (YES), then control proceeds to a step S3.

In the step S3, the console controller 66 decides whether the item "1",i.e., the item of entering material data, is selected in the displayedmenu image or not. If the item "1" is selected (YES), then control goesto a step S50, and if the item "1" is not selected (NO), then controlgoes to a step S4.

In the step S4, the console controller 66 decides whether the item "2",i.e., the item of recording material data, is selected in the displayedmenu image or not. If the item "2" is selected (YES), then control goesto a step S100, and if the item "2" is not selected (NO), then controlgoes back to the step S2.

In the step S50, the digital video data recording system operatesaccording to a material data entering routine. Thereafter, control goesto the step S100.

In the step S100, the digital video data recording system operatesaccording to a material data recording routine. Thereafter, control goesto a step S5.

In the step S5, the internal memory controller 68 reads the time codetable data from the table area 64b of the RAM 64 under the control ofthe table controller 71. The time code table data read from the tablearea 64b are supplied to the table controller 71. Based on the suppliedtime code table data, the table controller 71 decides whether there is amaterial to be processed next or not. If there is a material to beprocessed next (YES), then control goes back to the step S50, and ifthere is not a material to be processed next (NO), then control comes toan end.

G. Control Operation According to Material Data Entering Routine S50

FIG. 10 shows control operation of the digital video data recordingsystem according to the material data entering routine in the step S50shown in FIG. 9.

In a step S51 shown in FIG. 10, the internal memory controller 68 readsmaterial data information image data from the ROM 63 under the controlof the console controller 66. The material data information image dataread from the ROM 63 are supplied through the input/output port 65 tothe console 60, and displayed as a material data information image onthe display panel of the LCD 60a. Then, control proceeds to a step S52.

In the step S52, the console controller 66 decides whether the user haspressed the enter key (not shown) of the console 60 or not. If the userhas pressed the enter key (YES), then control jumps to a step S55. Ifthe user has not pressed the enter key (NO), then control proceeds to astep S53.

In the step S53, the console controller 66 decides whether the user haspressed numerical keys (not shown) of the console 60 or not. If the userhas pressed numerical keys (YES), then control proceeds to a step S54.If the user has not pressed numerical keys (NO), then control returns tothe step S52.

In the step S54, the internal memory controller 68 supplies a read/writecontrol signal to the RAM 64. The console 60 outputs numerical datacorresponding to the pressed numerical keys, and the numerical data aresupplied through the input/output port 65 and the bus assembly 62 to theRAM 64, which then stores the numerical data in the work area 64a.Thereafter, control goes back to the step S52.

In the step S55, when the console controller 66 recognizes that theenter key of the console 60 has been pressed by the user, the consolecontroller 60 indicates the pressing of the enter key to the tablecontroller 71. The table controller 71 controls the internal memorycontroller 68 to record the numerical data stored in the work area 64aof the RAM 64 as time code data in the time code table stored in thetable area 64b of the RAM 64. Thereafter, control proceeds to a stepS56.

In the step S56, the internal memory controller 68 reads the time codedata registered in the time code table in the table area 64b of the RAM64 under the control of the console controller 66. The time code datathus read are supplied through the input/output port 65 to the console60, and displayed on the display panel of the LCD 60a. Specifically, thetime code data registered by the user are displayed in a time codedisplay area in the material data information image. Control then leavesthe material data entering routine shown in FIG. 10, and goes back tothe step S100 shown in FIG. 9.

H. Control Operation According to Material Data Recording Routine S100

FIGS. 11 and 12 shows control operation of the digital video datarecording system according to the material data recording routine in thestep S100 shown in FIG. 9.

In a step S101 shown in FIG. 11, the encoder controller 74 supplies acontrol signal for connecting a main line and the motion detectorthrough the input/output port 65 to the video encoder 55. Then, controlproceeds to a step S102.

In the step S102, the reproducer controller 69 supplies a control signalrepresentative of a playback mode through the input/output port 65 tothe reproducer 52, causing the reproducer 52 to play back the materialdata. When the reproducer 52 starts the playback mode, time code datareproduced by the reproducer 52 are supplied through the input/outputport 65 to the reproducer controller 69. The reproducer controller 69now reads the supplied time code data. Then, control proceeds to a stepS103.

In the step S103, the reproducer controller 69 compares the time codedata read in the step S102 with the start time code data registered inthe time code table (see FIG. 7A) stored in the table area 64b of theRAM 64. If the time code data read in the step S102 are smaller than thestart time code data, then the reproducer controller 69 supplies acontrol signal indicative of a fast feed mode or a high-speed forwardplayback mode through the input/output port 65 to the reproducer 52. Ifthe time code data read in the step S102 are greater than the start timecode data, then the reproducer controller 69 supplies a control signalindicative of a rewind mode or a high-speed reverse playback modethrough the input/output port 65 to the reproducer 52. The fast feedmode or the high-speed forward playback mode corresponds to a LTC(Longitudinal Time Code), and the rewind mode or the high-speed reverseplayback mode corresponds to a VITC (Vertical Interval Time Code).

While accessing the material data, the reproducer controller 69 comparesthe time code data successively supplied from the reproducer 52 with thestart time code data, and supplies a control signal indicative of apause mode through the input/output port 65 to the reproducer 52 tobring the reproducer 52 into a pause mode when the time code datasuccessively supplied from the reproducer 52 represent a time code whichis a given period of time ahead of the start time code data. The abovegiven period of time includes a pre-roll time and a time spent after thereproducer controller 69 supplies the playback mode control signalthrough the input/output port 65 to the reproducer 52 until thereproducer 52 actually starts the playback mode. Thereafter, controlproceeds to a step S104.

In the step S104, the reproducer controller 69 supplies the playbackmode control signal through the input/output port 65 to the reproducer52, causing the reproducer 52 to start the playback mode. Thereafter,control proceeds to a step S105.

In the step S105, the GOP bit number detector 70 counts encoded datasupplied through the input/output port 65 from the video encoder 55, foreach GOP. Thereafter, control proceeds to a step S106.

In the step S106, the GOP bit number detector 70 decides whether thevalue of data at the start of a GOP in the encoded data supplied throughthe input/output port 65 from the video encoder 55 has a high level "1"or not, i.e., whether the start of a GOP is reached or not. If the valueof data has a high level "1" (YES), then control proceeds to a stepS107. If the value of data does not have a high level "1" (NO), thencontrol returns to the step S105. The decision step S106 is a step forthe GOP bit number detector 70 to detect the number of bits of encodeddata from the video encoder 55 for each GOP.

In the step S107, the GOP bit number detector 70 supplies detected GOPbit number data GOPb of the GOP to the RAM 64. Under the control of thetable controller 71, the internal memory controller 68 supplies aread/write control signal to the RAM 64 to register the GOP bit numberdata GOPb detected by the GOP bit number detector 70 in the GOP table(see FIG. 7B) in the table area 64b. Then, control proceeds to a stepS108.

In the step S108, the reproducer controller 69 reads the time code datasupplied from the reproducer 52 through the input/output port 65. Then,control proceeds to a step S109.

In the step S109, the reproducer controller 69 compares the time codedata supplied through the input/output port 65 from the reproducer 52with the end time code data registered in the time code table (see FIG.7A) in the table area 64b of the RAM 64, and decides whether thecompared time code data agree with each other or not. If the comparedtime code data agree with each other (YES), then control goes to a stepS110. If the compared time code data do not agree with each other (NO),then control goes back to the step S105.

In the step S110, the reproducer controller 69 supplies a control signalindicative of a stop mode through the input/output port 65 to thereproducer 52, stopping the playback mode of the reproducer 52.Thereafter, control proceeds to a step Sill.

In the step Sill, the GOP ratio calculator 72 controls the internalmemory controller 68 to read the GOP bit number data GOPb successivelyfrom the GOP table in the table area 64b of the RAM 64, and also readtotal bit number data of the recording medium which are stored in theROM 63. The GOP bit number data GOPb read from the GOP table and thetotal bit number data read from the ROM 63 are supplied to the GOP ratiocalculator 72. The GOP ratio calculator 72 calculates GOP ratios basedon the GOP bit number data GOPb and the total bit number data, andsupplies the calculated GOP ratios to the RAM 64. The GOP ratio data areregistered in the GOP table in the table area 64b of the RAM 64.Thereafter, control proceeds to a step S112 shown in FIG. 12.

In the step S112, the quantization controller 73 controls the internalmemory controller 68 to read the GOP ratio data successively from theGOP table in the table area 64b of the RAM 64, and also read the totalbit number data of the recording medium which are stored in the ROM 63.The GOP bit number data GOPb read from the GOP table and the total bitnumber data read from the ROM 63 are supplied to the quantizationcontroller 73. The quantization controller 73 calculates the numbers ofbits to be assigned to the respective GOPs based on all the GOP ratiodata and the total bit number data. The quantization controller 73supplies the calculated assignment bit number data to the RAM 64. Thetable controller 71 controls the internal memory controller 68 to supplya read/write control signal to the RAM 64, which stores the assignmentbit number data in the GOP table in the table area 64b thereof.Thereafter, control proceeds to a step S113.

In the step S113, the quantization controller 73 controls the internalmemory controller 68 to read the GOP bit number data GOPb and theassignment bit number data from the GOP table in the table area 64b. TheGOP bit number data GOPb and the assignment bit number data which areread from the GOP table are supplied to the quantization controller 73.Based on the GOP bit number data GOPb and the assignment bit numberdata, the quantization controller 73 determines quantization step sizesto be used in quantizing the image data of the respective GOPs. Then,control proceeds to a step S114.

In the step S114, the quantization controller 73 supplies thequantization step size data determined in the step S113 to the RAM 64.The table controller 71 controls the internal memory controller 68 tosupply a read/write control signal to the RAM 64, which stores thequantization step size data in the GOP table in the table area 64bthereof. Thereafter, control proceeds to a step S115.

In the step S115, the quantization controller 73 controls the internalmemory controller 68 to supply a read/write control signal for readingthe GOP bit number data GOPb and the assignment bit number data from theGOP table in the table area 64b. If no GOP bit number data GOPb and noassignment bit number data have been registered, then any data suppliedto the quantization controller 73 are all "0". The quantizationcontroller 73 decides whether the data read and supplied from the RAM 64are all "0" or not, i.e., whether all the quantization step size dataQST have been determined and registered or not. If all the quantizationstep size data QST have been registered (YES), then control proceeds toa step S116. If all the quantization step size data QST have not beenregistered (NO), then control returns to the step S113.

In the step S116, the encoder controller 74 supplies a control signalfor disconnecting the motion detector from the main line through theinput/output port 65 to the video encoder 55. Then, control goes to astep S117.

In the step 117, the reproducer controller 69 compares the time codedata read when the playback mode of the reproducer 52 is stopped in thestep S110 with the start time code data registered in the time codetable (see FIG. 7A) stored in the table area 64b of the RAM 64. If thetime code data read in the step S117 are smaller than the start timecode data, then the reproducer controller 69 supplies a control signalindicative of a fast feed mode or a high-speed forward playback modethrough the input/output port 65 to the reproducer 52. If the time codedata read in the step S117 are greater than the start time code data,then the reproducer controller 69 supplies a control signal indicativeof a rewind mode or a high-speed reverse playback mode through theinput/output port 65 to the reproducer 52.

While accessing the material data, the reproducer controller 69 comparesthe time code data successively supplied from the reproducer 52 with thestart time code data, and supplies a pause mode control signal throughthe input/output port 65 to the reproducer 52 to bring the reproducer 52into the pause mode when the time code data successively supplied fromthe reproducer 52 represent a time code which is a given period of timeahead of the start time code data. The above given period of timeincludes a pre-roll time and a time spent after the reproducercontroller 69 supplies the playback mode control signal through theinput/output port 65 to the reproducer 52 until the reproducer 52actually starts the playback mode. Thereafter, control proceeds to astep S118.

In the step S118, the reproducer controller 69 supplies the playbackmode control signal through the input/output port 65 to the reproducer52, causing the reproducer 52 to start the playback mode. Thereafter,control proceeds to a step S119.

In the step S119, the external memory controller 75 controls theinternal memory controller 68 to supply a read/write control signal tothe RAM 64 for thereby reading track/sector number data and data lengthdata registered with respect to the material ID of the material data tobe processed, from the hard disk table (see FIG. 7C) in the table area64b. The track/sector number data and the data length data are suppliedto the external memory controller 75. The external memory controller 75supplies track/sector number data and data length data for readingmotion vector data of frame image data to be processed, among thetrack/sector number data and the data length data which have beensupplied, through the input/output port 65 to the external memory 51. Inthis manner, the motion vector data of the frame image data aresuccessively read from the external memory 51. Then, control proceeds toa step S120.

In the step S120, the quantization controller 73 controls the internalmemory controller 68 to supply a read/write control signal to the RAM 64for thereby reading the quantization step size data QST from the GOPtable in the table area 64b thereof. The quantization step size data QSTread from the RAM 64 are supplied to the quantization controller 73. Thequantization controller 73 then supplies the quantization step size dataQST read from the RAM 64 through the input/output port 65 to the videoencoder 55. Then, control proceeds to a step S121.

In the step S121, the reproducer controller 69 reads time code datasupplied from the reproducer 52 through the input/output port 65. Then,control proceeds to a step S122.

In the step S122, the reproducer controller 69 compares the time codedata supplied through the input/output port 65 from the reproducer 52with the end time code data registered in the time code table (see FIG.7A) in the table area 64b of the RAM 64, and decides whether thecompared time code data agree with each other or not. If the comparedtime code data agree with each other (YES), then control goes to a stepS123. If the compared time code data do not agree with each other (NO),then control goes back to the step S119.

In the step S123, the reproducer controller 69 supplies a stop modecontrol signal through the input/output port 65 to the reproducer 52,stopping the playback mode of the reproducer 52. Control then leaves thematerial data recording routine shown in FIGS. 11 and 12 and returns tothe main routine shown in FIG. 9.

I. Internal Structure and Operation of Video Encoder 55 Shown in FIG. 6

FIG. 13 is a block diagram of the video encoder 55 in the digital videodata recording system shown in FIG. 6.

Internal Structure of Video Encoder 55:

As shown in FIG. 13, the video encoder 55 comprises frame memories 101,102, 103 for successively storing image data supplied through an inputterminal 100, a selector 104 for selectively outputting the image datafrom the frame memories 101, 102, 103 according to a control signal froma controller 128, a motion detecting block for effecting a motiondetecting process to produce motion vector data, a motion compensatingblock for effecting a motion compensating process based on the motionvector data produced by the motion detecting block, an adder 107 forcalculating differential data between macroblock data having a size of16 lines×16 pixels supplied from the selector 104 and motion-compensatedmacroblock data having a size of 16 lines×16 pixels supplied from themotion compensating block, an inter-/intra-frame decision unit 108 forselecting either the macroblock data from the selector 104 or thedifferential data from the adder 107, a switch 109 for selecting eitherthe macroblock data from the selector 104 or the differential data fromthe adder 107 under the control of the inter-/intra-frame decision unit108, a compressing and encoding block for compressing and encodingoutput data from the switch 109, and the controller 128 for controllingthe above components.

Image data are successively supplied through the input terminal 100, andstored in the frame memory 101 during a frame period. In a next frameperiod, the image data read from the frame memory 101 are successivelystored in the frame memory 102. In a further next frame period, theimage data read from the frame memory 102 are successively stored in theframe memory 103. After elapse of the periods of three frames,therefore, the frame memory 103 stores the image data of a first frame,the frame memory 102 stores the image data of a second frame, and theframe memory 101 stores the image data of a third frame. If it isassumed that the frame memory 102 outputs the image data of a presentframe, then the frame memory 101 outputs the image data of a futureframe, and the frame memory 103 outputs the image data of a past frame.The image data of each macroblock outputted from the frame memory 101are referred to as macroblock data of a following frame, the image dataof each macroblock outputted from the frame memory 102 are referred toas macroblock data of a present frame, and the image data of eachmacroblock outputted from the frame memory 103 are referred to asmacroblock data of a preceding frame.

The compressing and encoding block comprises a DCT (Discrete cosineTransform) circuit 110 for converting the macroblock data or thedifferential data supplied from the switch 109, in each block of 8lines×8 pixels, from DC data into coefficient data of harmonic ACcomponents, a quantizer 111 for quantizing coefficient data from the DCTcircuit 110 with quantization step size data QST supplied from thecontroller 128, a VLC (Variable Length Code) encoder 112 for convertingcoefficient data from the quantizer 111 according to the Huffmanencoding process, the runlength encoding process, or the like, and anoutput encoder 113 for adding inner and outer parity bits to thevariable-length-coded data outputted from the VLC encoder 112 forrecording or transmission, thereby converting the data into a train ofdata in a product code format.

The motion detecting block comprises a motion detector 105 for effectinga motion detecting process on the macroblock of the following frame fromthe frame memory 101 and the macroblock of the present frame from theframe memory 102 to produce motion vector data, and a motion detector106 for effecting a motion detecting process on the macroblock of thepreceding frame from the frame memory 103 and the macroblock of thepresent frame from the frame memory 102 to produce motion vector data.

The motion compensating block comprises an inverse quantizer 115, anIDCT (Inverse Discrete Cosine Transform) circuit 116, an adder 117, aswitch 118, a frame memory 119, a motion compensator 120, a switch 121,a frame memory 122, a motion compensator 123, a switch 124, and a switch127.

The inverse quantizer 115 inversely quantizes coefficient data from thequantizer 111 to obtain the coefficient data produced by the DCT circuit110. The IDCT circuit 116 converts the coefficient data supplied fromthe inverse quantizer 115 into original macroblock data or differentialdata. The adder 117 adds the output data from the IDCT circuit 116 andmotion-compensated macroblock data to each other. The switch 118selectively supplies the output data from the adder 117 and the outputdata from the IDCT circuit 116 to the frame memory 119 based on aswitching control signal from the inter-/intra-frame decision unit 108.

The motion compensator 120 selects appropriate macroblock data amongframe data stored in the frame memory 119 based on the motion vectordata which have been supplied from the motion detector 105 or read fromthe external memory 51 shown in FIG. 6 and supplied from theinput/output port 65 of the system controller 59 through an inputterminal 121i and the switch 121, and outputs the selected macroblockdata as motion-compensated macroblock data. The switch 121 selectivelysupplies the motion vector data from the motion detector 105 and themotion vector data read from the external memory 51 shown in FIG. 6 andsupplied to the system controller 59 and then supplied from the systemcontroller 59, to the motion compensator 120 based on a switchingcontrol signal supplied from the controller 128.

The motion compensator 120 has an input terminal for being supplied withthe motion vector data, the input terminal being connected to a movablecontact "c" of the switch 121. The switch 121 has a fixed contact "a"connected to an output terminal of the motion detector 105, and anotherfixed contact "b" connected through the input terminal 121i to theinput/output port 65 shown in FIG. 6.

The motion compensator 123 selects appropriate macroblock data amongframe data stored in the frame memory 122 based on the motion vectordata which have been supplied from the motion detector 106 or read fromthe external memory 51 shown in FIG. 6 and supplied from theinput/output port 65 of the system controller 59 through an inputterminal 124i and the switch 124, and outputs the selected macroblockdata as motion-compensated macroblock data. The switch 124 selectivelysupplies the motion vector data from the motion detector 106 and themotion vector data read from the external memory 51 shown in FIG. 6 andsupplied to the system controller 59 and then supplied from the systemcontroller 59, to the motion compensator 123 based on a switchingcontrol signal supplied from the controller 128.

The motion compensator 123 has an input terminal for being supplied withthe motion vector data, the input terminal being connected to a movablecontact "c" of the switch 124. The switch 124 has a fixed contact "a"connected to an output terminal of the motion detector 106, and anotherfixed contact "b" connected through the input terminal 124i to theinput/output port 65 shown in FIG. 6.

An adder 125 adds the motion-compensated macroblock data from the motioncompensators 120, 123. A 1/2 multiplier 126 multiplies sum output datafrom the adder 125 by a coefficient "1/2". The switch 127 selectivelysupplies the motion-compensated macroblock data from the motioncompensator 120, the motion-compensated macroblock data from the motioncompensator 123, and the average data from the 1/2 multiplier 126 to theadder 107 according to a switching control signal from the controller128.

The inter-/intra-frame decision unit 108 compares variance values of themacroblock data from the selector 104 and the differential data from theadder 107, and selects a smaller variance value.

The motion compensator 120 effects a motion compensating process on themacroblock data of a frame (a future frame) which follows in time themacroblock data of a frame outputted from the selector 104. The motioncompensator 123 effects a motion compensating process on the macroblockdata of a frame (a past frame) which precedes in time the macroblockdata of a frame outputted from the selector 104.

The macroblock data of frames successively outputted from the selector104 are supplied to the adder 107, which calculates differential databetween the macroblock data from the selector 104 and an either one ofthe data from the motion compensator 120, the motion compensator 123,and the 1/2 multiplier 126 for encoding purpose. The differential datafrom the adder 107 are differential data between frames. Since thedifferential data between frames are encoded, the encoding processtherefor is referred to as the inter-frame encoding process. Since themacroblock data from the selector 104 are encoded as they are, theencoding process therefor is referred to as the intra-frame encodingprocess.

It is assumed in the description which follows that a B picture isproduced by calculating differential data between image data whichprecede and follow the B picture, and a P picture is produced from an Ipicture. Actually, macroblock data of the best encoding efficiency areselected for encoding among the macroblock data which have beencompensated by a forward motion compensating process, an interpolatingmotion compensating process, and a backward motion compensating process,and for decoding, and the data of each macroblock are compensated fordecoding in the same manner as they are compensated for encoding.

Specifically, differential data in one B picture are data produced whenthe macroblock data which have been compensated by either the forwardmotion compensating process, the interpolating motion compensatingprocess, or the backward motion compensating process, are subtractedfrom the macroblock data to be encoded, and differential data in one Ppicture are data produced when the macroblock data which have beencompensated by either the forward motion compensating process or thebackward motion compensating process, are subtracted from the macroblockdata to be encoded. Therefore, the words "image data" used hereinbelowmean "image data of each macroblock" except when the words "image data"are used to denote image data of each original frame.

Operation for Producing Motion Vector Data:

Operation of the video encoder shown in FIG. 13 for producing motionvector data will be described below.

For producing motion vector data, the controller 128 generates switchingcontrol signals based on control signals supplied from the systemcontroller 59 shown in FIG. 6 to connect the motion detector 105 and themotion compensator 120 and the motion detector 106 and the motioncompensator 123, and supplies the switching control signals to theswitches 121, 124, respectively, to connect the movable contacts "c"thereof to the respective fixed contacts "a".

Image data supplied to the input terminal 100 are stored successively inthe frame memories 101, 102, 103. The motion detector 105 effects amotion detecting process on macroblock data of a following frame readfrom the frame memory 101 and macroblock data of a present frame readfrom the frame memory 102, and produces motion vector data based on theresult of the motion detecting process. The motion vector data aresupplied through an output terminal 121o to the system controller 59 andalso through the switch 121 to the motion compensator 120.

The motion detector 106 effects a motion detecting process on macroblockdata of a preceding frame read from the frame memory 103 and themacroblock data of the present frame read from the frame memory 102, andproduces motion vector data based on the result of the motion detectingprocess. The motion vector data are supplied through an output terminal124o to the system controller 59 and also through the switch 124 to themotion compensator 120.

The motion vector data supplied to the system controller 59 through theoutput terminals 121o, 124o are then supplied through the systemcontroller 59 to the external memory 51 shown in FIG. 6, and stored inthe external memory 51.

After motion vector data representing motion vectors between all themacroblock data of the present frame and all the macroblock data of thefollowing frame and motion vector data representing motion vectorsbetween all the macroblock data of the present frame and all themacroblock data of the preceding frame are produced, the video encoderstarts an encoding process.

The encoding process of encoding the macroblock data outputted from theselector 104 will be described below also with reference to FIGS. 15Aand 15B. It is assumed in the following description that switchingbetween inter- and intra-frame encoding processes is effected for eachframe.

FIG. 15A shows frames of image data supplied to the input terminal 100.FIG. 15B shows the order in which image data are outputted from theselector 104 and encoded. Numerals in the frames the order of thesupplied frames, and alphabetical letters in the frames indicate thatthe image data of frames carrying "I" become a B picture when encoded,the image data of frames carrying "I" become a I picture when encoded,and the image data of frames carrying "P" become a P picture whenencoded.

The image data which are pointed by the arrows are image data which areencoded, and the image data from which the arrows are originated areimage data which are used to encode the above image data. The arrows inFIG. 15A indicate which frame image data are used as predictive imagedata for encoding the image data of the frames indicated by the arrows.For example, the image data of the third frame which will be encodedinto a B picture are encoded on the basis of differential data betweenthe image data of the third frame and either the image data of thesecond frame which will be encoded into an I picture, or the image dataof the fourth frame which will be encoded into a P picture, or the sumof the image data of these two frames. For the P pictures, any arrowsfor indicating frames for use as perceptive image data are omitted fromillustration.

The frames in a GOP 2 shown in FIGS. 15A and 15B will be described byway of example below. It is assumed that the frame memory 122 shown inFIG. 13 stores the image data P4 used as predictive image data for theimage data B5 shown in FIG. 15A, and, for illustrative purpose,predictive image data from the 1/2 multiplier 126 are used at all timesfor being encoded into B pictures.

The image data I6, shown in FIG. 15B, of each of macroblock data areoutputted successively from the selector 104. At this time, the movablecontacts "c" of the switches 109, 118 are connected to the fixedcontacts "b" thereof. Therefore, the macroblock data of the image dataI6 pass through the switch 109, are processed by the DCT circuit 110,the quantizer 111, the VLC encoder 112, and the output encoder 113, andare outputted from an output terminal 114.

Coefficient data of the image data I6 which are quantized by thequantizer 111 are converted back into the original macroblock datahaving a size of 8 lines×8 pixels by the inverse quantizer 115 and theIDCT circuit 116, and the original macroblock data are supplied throughthe switch 118 to the frame memory 119 and successively stored therein.

After the image data P4 are stored in the frame memory 122 and the imagedata I6 are stored in the frame memory 119, predictive image data fromthe 1/2 multiplier 126 are subtracted from the image data B5 outputtedfrom the selector 104 by the adder 107, which produces differential datathat are encoded. Before image data B5 are outputted from the selector104, the image data I6 are stored in the frame memory 101, the imagedata B5 are stored in the frame memory 102, and the image data P4 arestored in the frame memory 103.

The motion detector 105 effects a motion detecting process on eachmacroblock of the image data B5 stored in the frame memory 102 and eachmacroblock of the image data I6 stored in the frame memory 101,producing motor vector data indicative of which part (macroblock data)of the image data I6 is in agreement with each of the macroblocks of theimage data B5. The motion vector data of each macroblock are used in themotion compensator 120 to successively read the corresponding macroblockdata in the image data I6 stored in the frame memory 119, i.e., toeffect a motion compensating process.

The motion detector 106 effects a motion detecting process on eachmacroblock of the image data B5 stored in the frame memory 102 and eachmacroblock of the image data P4 stored in the frame memory 103,producing motor vector data indicative of which part (macroblock data)of the image data P4 is in agreement with each of the macroblocks of theimage data B5. The motion vector data of each macroblock are used in themotion compensator 123 to successively read the corresponding macroblockdata in the image data P4 stored in the frame memory 122, i.e., toeffect a motion compensating process.

As the macroblock data of the image data B4 are outputted from theselector 104, the 1/2 multiplier 126 outputs average data indicative ofthe average of the macroblock data of the motion-compensated image dataI6 from the motion compensator 120 and the macroblock data of themotion-compensated image data P4 from the motion compensator 123, andsupplies the average data through the switch 127 to the adder 107. Theadder 107 subtracts the supplied average data from the macroblock dataof the image data B5, thereby producing differential data that areencoded by the compressing and encoding block. The above process iscarried out with respect to all the macroblock data of the image dataB5.

The image data P8 are encoded next. Before the image data P8 areoutputted from the selector 104, the image data P8 are stored in theframe memory 101, the image data B7 are stored in the frame memory 102,and the image data I6 are stored in the frame memory 103.

The motion detector 105 effects a motion detecting process on eachmacroblock of the image data B7 stored in the frame memory 102 and eachmacroblock of the image data P8 stored in the frame memory 101,producing motor vector data indicative of which part (macroblock data)of the image data P8 is in agreement with each of the macroblocks of theimage data B7. The motion vector data of each macroblock are used in themotion compensator 120 to successively read the corresponding macroblockdata in the image data I6 stored in the frame memory 122, i.e., toeffect a motion compensating process.

As the macroblock data of the image data P8 are outputted from theselector 104, the motion-compensated macroblock data of the image dataI6 are supplied from the motion compensator 120 through the switch 127to the adder 107. Therefore, the adder 107 subtracts themotion-compensated macroblock data of the image data I6 from themacroblock data of the image data P8, thereby producing differentialdata that are encoded by the compressing and encoding block andoutputted from the output terminal 114. The above process is carried outwith respect to all the macroblock data of the image data P8. After theimage data P8 are encoded, the image data I6 stored in the frame memory119 are stored in the frame memory 122.

During the above process, the encoded differential data from thequantizer 111 are converted back to the original differential data bythe inverse quantizer 115 and the IDCT circuit 116, and the originaldifferential data are supplied to the adder 117. The adder 117 adds theoriginal differential data and the motion-compensated macroblock datasupplied from the motion compensator 120 through the switch 127, thusconverting the differential data back to the macroblock data of theimage data P8. The macroblock data of the image data P8 are suppliedthrough the switch 118 to the frame memory 119. The above process iscarried out until the storage of the image data P8 into the frame memory119 is finished.

The image data B7 are encoded next. Before the image data B7 areoutputted from the selector 104, the image data P8 are stored in theframe memory 101, the image data B7 are stored in the frame memory 102,and the image data I6 are stored in the frame memory 103.

The motion detector 105 effects a motion detecting process on eachmacroblock of the image data B7 stored in the frame memory 102 and eachmacroblock of the image data P8 stored in the frame memory 101,producing motor vector data indicative of which part (macroblock data)of the image data P8 is in agreement with each of the macroblocks of theimage data B7. The motion vector data of each macroblock are used in themotion compensator 120 to successively read the corresponding macroblockdata in the image data P8 stored in the frame memory 119, i.e., toeffect a motion compensating process.

The motion detector 106 effects a motion detecting process on eachmacroblock of the image data B7 stored in the frame memory 102 and eachmacroblock of the image data I6 stored in the frame memory 103,producing motor vector data indicative of which part (macroblock data)of the image data I6 is in agreement with each of the macroblocks of theimage data B7. The motion vector data of each macroblock are used in themotion compensator 123 to successively read the corresponding macroblockdata in the image data I6 stored in the frame memory 122, i.e., toeffect a motion compensating process.

As the macroblock data of the image data B7 are outputted from theselector 104, the 1/2 multiplier 126 outputs average data indicative ofthe average of the macroblock data of the motion-compensated image dataP8 from the motion compensator 120 and the macroblock data of themotion-compensated image data I6 from the motion compensator 123, andsupplies the average data through the switch 127 to the adder 107. Theadder 107 subtracts the supplied average data from the macroblock dataof the image data B7, thereby producing differential data that areencoded by the compressing and encoding block and outputted from theoutput terminal 114. The above process is carried out with respect toall the macroblock data of the image data B7. After the image data B7are encoded, the image data P8 stored in the frame memory 119 are storedin the frame memory 122.

The image data of each frame of the GOP 2 are encoded in the mannerdescribed above. The image data of the frames of the other GOPs areencoded in the same manner. The controller 128 adds the motion vectordata from the motion detectors 105, 106, data indicative of a motioncompensation type (or data indicative of the data subtracted in theencoding process), and data indicative of a picture type to thecompressed data or compressed differential data supplied to the outputencoder 113, and also adds data indicative of the start of each GOP anddata indicative of the encoding order to the compressed data orcompressed differential data. The compressed data or compresseddifferential data to which the above data are added are converted intodata in a product code format by the output encoder 113, and thensupplied through an input/output terminal 128b to the system controller59 shown in FIG. 6. From the compressed data or compressed differentialdata supplied to the system controller 59, there is detected the numberof bits of each GOP by the GOP bit number detector 70 shown in FIG. 6.

Recording Operation of Video Encoder 55:

Operation of the video encoder 55 shown in FIG. 13 in a recordingprocess will be described below. Only the encoding of frame image dataof a B picture will be described.

In the recording process, the controller 128 generates switching controlsignals based on control signals supplied from the system controller 59shown in FIG. 6 to connect the motion detector 105 to the motioncompensator 120 and disconnect the motion detector 106 from the motioncompensator 123, and supplies the switching control signals to theswitches 121, 124, respectively, to connect the movable contacts "c"thereof to the respective fixed contacts "b". The controller 128 alsosupplies control signals to the motion detectors 105, 106 to stop theirmotion detecting process based on the control signals supplied from thesystem controller 59. The motion detectors 105, 106 now stop theirmotion detecting process although they supply read/write control signalsto the frame memories 101, 102, 103.

Under the control of the external memory controller 75 of the systemcontroller 59, motion vector data read from the external memory 51 andsupplied through the system controller 59 are supplied through the inputterminal 121i and the switch 121 to the motion compensator 120 andthrough the input terminal 124i and the switch 124 to the motioncompensator 123. The motion vector data are also supplied throughinput/output terminal 128b to the controller 128.

Image data supplied to the input terminal 100 are successively stored inthe frame memories 101, 102, 103. The motion compensator 120 readsmacroblock data represented by the motion vector data supplied throughthe input terminal 121i and the switch 121 from the frame memory 119.The motion compensator 123 reads macroblock data represented by themotion vector data supplied through the input terminal 124i and theswitch 124 from the frame memory 122.

The macroblock data read from the frame memory 119 by the motioncompensator 120 and the macroblock data read from the frame memory 122by the motion compensator 123 are supplied to the adder 125, which addsthe supplied macroblock data. Sum output data from the adder 125 aresupplied to the 1/2 multiplier 126, which multiplies the supplied databy the coefficient "1/2", thus averaging the data. The average data aresupplied through the switch 127 to the adder 107, which subtracts theaverage data from the macroblock data of the present frame supplied fromthe selector 104, thus producing differential data. The differentialdata are supplied through the switch 109 to the DCT circuit 110, whichconverts the differential data into coefficient data ranging from DC toharmonic AC components. The coefficient data from the DCT circuit 110are supplied to the quantizer 111.

The quantization step size data QST from the system controller 59 aresupplied through the input/output terminal 128b to the controller 128,which supplies the quantization step size data QST to the quantizer 111.The quantizer 111 quantizes the coefficient data from the DCT circuit110 based on the quantization step size data QST.

The controller 128 adds the motion vector data supplied from theexternal memory 51 through the system controller 59, data indicative ofa motion compensation type (or data indicative of the data subtracted inthe encoding process), and data indicative of a picture type to thecompressed data or compressed differential data supplied to the outputencoder 113, and also adds data indicative of the start of each GOP anddata indicative of the encoding order to the compressed data orcompressed differential data. The compressed data or compresseddifferential data to which the above data are added are converted intodata in a product code format by the output encoder 113, and thenoutputted through the output terminal 114 and supplied through theinterface 57 to the master generator 58 shown in FIG. 6, which recordsthe supplied data on a master.

J. Internal Structure and Operation of Motion Detectors 105, 105 Shownin FIG. 13

An example of the motion detectors 105, 106 shown in FIG. 13 will bedescribed below with reference to FIG. 14. The motion detector shown inFIG. 14 effects a motion detecting process according to a methodreferred to as block matching.

In the video encoder shown in FIG. 13, the frame memory 102 serves as aframe memory for storing present frame image data, the frame memory 101as a frame memory for storing past frame image data, and the framememory 103 as a frame memory for storing future frame image data.

When the motion detecting process is to be effected on the frame imagedata of the future frame stored in the frame memory 101 and the frameimage data of the present frame stored in the frame memory 102, theframe image data stored in the frame memory 102 serve as the frame imagedata of a reference frame and the frame image data stored in the framememory 101 serve as the frame image data of the present frame. When themotion detecting process is to be effected on the frame image data ofthe present frame stored in the frame memory 102 and the frame imagedata of the past frame stored in the frame memory 103, the frame imagedata stored in the frame memory 103 serve as the frame image data of areference frame and the frame image data stored in the frame memory 102serve as the frame image data of the present frame.

When the motion detecting process is to be effected on the frame imagedata of an nth frame and the frame image data of an (n-1)th frame, aframe memory 221 shown in FIG. 14 corresponds to the frame memory 102 ofthe video encoder shown in FIG. 13, and a frame memory 223 shown in FIG.14 corresponds to the frame memory 103 of the video encoder shown inFIG. 13. When the motion detecting process is to be effected on theframe image data of the nth frame and the frame image data of an (n+1)thframe, the frame memory 221 shown in FIG. 14 corresponds to the framememory 101 of the video encoder shown in FIG. 13, and the frame memory223 shown in FIG. 14 corresponds to the frame memory 102 of the videoencoder shown in FIG. 13.

A controller 232 shown in FIG. 14 corresponds to the controller 128shown in FIG. 13.

Internal Structure of the Motion Detector:

The motion detector shown in FIG. 14 has the present frame memory 221for storing the image data of a present frame, the reference framememory 223 for storing the image data of a preceding frame (a referenceframe), an address generator 233 for supplying different addressessuccessively to the reference frame memory 223, an adder 224 forsubtracting pixel data of a reference macroblock supplied from thereference frame memory 223 from pixel data of a macroblock in questionof the present frame, producing differential data, an absolute circuit225 for producing the absolute value of the differential data from theadder 224, a latch 227 for holding the absolute value data from theabsolute circuit 225, an adder 226 for adding output data from theabsolute circuit 225 and latched output data from the latch 227 toproduce differential absolute sum data of for reference macroblock, amemory 228 for storing the differential absolute sum data from the adder226, a minimum value detector 229 for detecting a minimum value of thedifferential absolute sum data stored in the memory 228, a motion vectordetector 230 for producing motion vector data corresponding to onemacroblock in question based on the minimum value of the differentialabsolute sum data from the minimum value detector 229 and the addressesof the reference macroblock and the macroblock in question from whichthe minimum value of the differential absolute sum data can be obtained,and supplying the motion vector data to the controller 232, the systemcontroller 59 shown in FIG. 6, the controller 128 and the switch 121shown in FIG. 13, and the controller 232 for controlling an addressgenerator 233 based on the minimum value of the differential absolutesum data from the minimum value detector 229 and the motion vector datafrom the motion vector detector 230, and controlling the writing ofimage data into the present frame memory 221 and the reading of imagedata stored therein.

The motion vector detector 230 produces motion vector data by readingmotion vector data, which are obtained from the addresses of thereference macroblock and the macroblock in question from which theminimum value of the differential absolute sum data can be obtained,e.g., data of distances of movement in vertical and horizontaldirections, from a ROM or the like as a conversion table.

Operation of Motion Detector:

Under the control of the controller 232, pixel data of a macroblock (8×8pixels or 16×16 pixels) as a macroblock in question are successivelyrepeatedly read from the present frame memory 221. Under the control ofthe controller 232, the address generator 233 establishes a search areain a storage space of the reference frame memory 223, establishes areference block having the same size as the above macroblock in thesearch area, and successively supplies address data for successivelyreading pixel data in the reference block to the reference frame memory223. When all the pixel data in the established reference block havebeen read, the address generator 233 supplies address data to thereference frame memory 223 thereby to shift the position of thereference block one pixel in the search area, and then successivelysupplies address data to the reference frame memory 223 to read thepixel data in the reference block which has positionally been shiftedone pixel.

The adder 224 subtracts the pixel data in the reference block read fromthe reference frame memory 223 from the pixel data in the block inquestion read from the present frame memory 221. Differential dataoutputted from the adder 224 are supplied to the absolute value circuit225, which produces absolute value data supplied through the adder 226to the latch 227, which has already stored differential absolute sumdata from the adder 226. Therefore, differential absolute sum databetween the block in question in the present frame memory 221 and onereference block in the reference frame memory 223 are successivelystored in the memory 288. Eventually, the memory 288 stores as manydifferential absolute sum data as the number of many blocks in questionwhich are successively shifted one pixel in the search area.

When all calculations relative to the pixel data of one block inquestion and the pixel data of a plurality of reference macroblocks inone search area are completed, the minimum value detector 229 selectsthe minimum differential absolute sum data among all the differentialabsolute sum data in the memory 228, and supplies the selected minimumdifferential absolute sum data to the motion vector detector 230 andsupplies a control signal to the controller 232 for starting the processfor a next block in question.

The differential absolute sum data from the minimum value detector 229are supplied to the motion vector detector 230. The motion vectordetector 230 produces motion vector data based on the addresses of thereference macroblock and the macroblock in question from which theminimum differential absolute sum data can be obtained by the minimumvalue detector 229. The motion vector data produced by the motion vectordetector 230 are supplied to the controller 232, and supplied through anoutput terminal 231 to the motion compensators 120, 123 shown in FIG. 13and through the system controller 59 to the external memory 51. Afterthe controller 232 establishes a search area in the same process asdescribed above, the controller 232 controls the address generator 233and the present frame memory 221 for effecting calculations on the pixeldata in a next macroblock in question and the pixel data in a referenceblock.

The above block matching technique is disclosed in U.S. Pat. No.4,897,720.

K. Predictive Directions in Decoding Image Data Encoded by Video Encoder55 Shown in FIG. 13

A process of decoding image data encoded by the video encoder 55 shownin FIG. 13 will be described with reference to FIG. 15C.

Encoded data of a B or P picture are decoded using the same frame imagedata as the frame image data used in the encoding process, as shown inFIG. 15C. Motion vector data which are added to encoded frame image datain the encoding process are used to extract macroblock data used in theencoding process from frame image data used in the decoding process.

For example, as s how n in FIG. 15C, the macroblock data of the encodeddata B5 are decoded by adding average data produced when macroblock dataread from the frame image data P4 used in the encoding process based onthe motion vector data and macroblock data read from the frame imagedata I6 based on the motion vector data are added and the sum data aremultiplied by a coefficient "1/2", and differential data of the encodeddata B5.

The image data of the frames of GOPs are successively decoded asdescribed above.

The decoded image data of the frames of GOPs are read in the order ofB1, I2, B3, P4, B5, I6, B7, P7, P8, B9, I10, B11, P12, therebyrearranging the image data in the GOPs. It is to be noted that the orderof the GOPs remains the same, whereas the image data in each of the GOPsare rearranged into the true order of frames before they are encoded.

Advantages of 1st Embodiment:

According to the first embodiment, in the digital video data recordingsystem shown in FIG. 6, frame image data to be recorded are suppliedtwice to the video encoder 55. In the first cycle of operation, motionvector data are produced and stored in the external memory 51, thenumber of bits of encoded data is detected for each GOP to determine aGOP ratio, the number of all bits of the storage medium is divided andassigned to the GOPs, and quantization step size data are determinedbased on the assigned bit numbers. In the second cycle of operation, themotion vector data stored in the external memory 51 in the first cycleare read, the motion compensating process is effected using the readmotion vector data, data produced by the motion compensating process areconverted into coefficient data by the DCT circuit 110, thereafter thecoefficient data are quantized based on the quantization step size data,the quantized coefficient data are VLC-encoded, the VLC-encoded data areencoded for outputting purpose, and the encoded data are recorded on amaster by the master generator 58.

Therefore, the frame image data can be optimally encoded depending onthe number of bits thereof, and all the image data to be recorded can berecorded on the storage medium. In the recording process, since themotion detecting processes of the motion detectors 105, 106 are stopped,the consumption of electric energy by the digital video data recordingsystem is largely reduced.

L. Concept of 2nd Embodiment

FIG. 16 illustrates in block form an image information recordingapparatus, showing a conceptual arrangement of a second embodiment ofthe present invention.

Structure:

The image information recording apparatus shown in FIG. 16 differs fromthe image information recording apparatus shown in FIG. 5 in that theimage information recording apparatus shown in FIG. 16 does not have thefirst memory 2 in the image information recording apparatus shown inFIG. 5. Those parts shown in FIG. 16 which are identical to those shownin FIG. 5 are denoted by identical reference characters, and will not bedescribed in detail below.

In the case where the variable-rate encoding process is employed in theimage information recording apparatus shown in FIG. 16, motion vectordata and compression ratio information indicative of a compression ratiofor each of one or more image information items are determined in thepreprocessing procedure and stored in the external memory 8, and whenthe image information from the signal source 1 is to be recorded on therecording medium by the recorder 17, the motion vector data stored inthe external memory 8 are used. Thus, the image information recordingapparatus is not required to have the motion detector 3 carry out amotion detecting process. The compression ratio information determinedin the preprocessing procedure is used to effect an encoding process.Only the second memory 14 is used when the encoding process is carriedout to detect motion vector data and when a motion compensating processis carried out using the motion vector data read from the externaldevice 8.

Operation in Preprocessing Procedure:

Operation of the image information recording apparatus shown in FIG. 16in the preprocessing procedure will be described below.

The switches 4, 5, 6 are turned on by switch control signals from thecontroller 7. The motion detector 3 and the signal source 1, the motiondetector 3 and the second memory 14, and the motion detector 3 and theexternal memory 8 are electrically connected when the respectiveswitches 4, 6, 5 are turned on.

The signal source 1 starts to output image information under the controlof the controller 7. The image information outputted from the signalsource 1 is encoded by the encoder 11, thereafter decoded by the decoder13, added to macroblock data from the delay unit 16, and then suppliedto and stored in the second memory 14. The image information outputtedfrom the signal source 1 is also supplied to the motion detector 3 asindicated by the arrow Px1 in FIG. 16. At the same time, the imageinformation stored in the second memory 14 is read therefrom andsupplied to the motion detector 3 as indicated by the arrow Px2 underthe control of the controller 7. The motion detector 3 effects a motiondetecting process on the image information from the signal source 1 andthe image information from the second memory 14, and produces motionvector data based on the result of the motion detecting process. Themotion vector data generated by the motion detector 3 are supplied tothe external memory 8 as indicated by the arrow Px3. The external memory8 stores the motion vector data supplied from the motion detector 3according to a control signal supplied from the controller 7. Thecontroller 7 determines a compression ratio for one or more images. Theabove preprocessing procedure is carried out with respect to all imagedata to be recorded.

Operation in Recording Process:

operation of the image information recording apparatus shown in FIG. 16in the recording process will be described below.

The switches 4, 5, 6 are turned off by switch control signals from thecontroller 7. The motion detector 3 and the signal source 1, the motiondetector 3 and the second memory 14, and the motion detector 3 and theexternal memory 8 are electrically disconnected when the respectiveswitches 4, 6, 5 are turned off.

The signal source 1 starts to output image information under the controlof the controller 7. The image information outputted from the signalsource 1 is supplied to the delay unit 9 as indicated by the arrow Py1.The image information is then delayed by the delay unit 9 for a periodof time which is required by a motion compensating process in the motioncompensator 15, and then supplied to the adder 10. The image informationwhich is supplied to the adder 10 for the first time is outputted as itis from the adder 10 because no image information is supplied from themotion compensator 15 to the adder 10. The image information outputtedfrom the adder 10 is supplied to the encoder 11 as indicated by thearrow Py2, and encoded by the encoder 11. The encoded image informationis supplied to the decoder 12 as indicated by the arrow Py3, and decodedback to the original image information by the decoder 12. The decodedimage information is supplied to the adder 13.

The image information which is supplied to the adder 13 for the firsttime is outputted as it is from the adder 13 because no imageinformation is supplied from the motion compensator 15 through the delayunit 16 to the adder 13. The image information outputted from the adder13 is supplied to the second memory 14, and stored in the second memory14 according to a control signal from the controller 7.

The image information successively outputted from the signal source 1 isdelayed for the above delay time by the delay unit 9, and then suppliedto the adder 10 as indicated by the arrow Py1. At the same time, themotion vector data stored in the external memory 8 are read therefromaccording to a control signal that is supplied from the controller 7 tothe external memory 8. The motion vector data read from the externalmemory 8 are supplied to the motion compensator 15 as indicated by thearrow Py4. The motion compensator 15 reads image information representedby the motion vector data supplied from the external memory 8 from thesecond memory 14 as indicated by the arrow Py5. The image informationread from the second memory 14 is supplied to the adder 10 as indicatedby the arrow Py6.

The adder 10 subtracts the image information read from the second memory14 by the motion compensator 15 from the image information supplied fromthe signal source 1 through the delay unit 9. Differential dataoutputted as a resultant sum from the adder 10 are supplied to theencoder 11 as indicated by the arrow Py2, and encoded by the encoder 11based on the compression ratio information which has been determined inthe preprocessing procedure. The encoded image information from theencoder 11 is then supplied to the recorder 17 as indicated by the arrowPy7, and recorded on the recording medium by the recorder 17.

The image information read by the motion compensator 15 is also suppliedthrough the delay unit 16 to the adder 13 as indicated by the arrow Py8.The adder 13 adds the image information from the decoder 12 and theimage information from the delay unit 16. Sum output data from the adder13 are supplied to the second memory 14 as indicated by the arrow Py9,and stored in the second memory 14. The above recording process iscarried out with respect to all image data to be recorded.

Advantages of the Concept of 2nd Embodiment:

As can be seen from the above explanation of the concept of the secondembodiment, the image information recording apparatus shown in FIG. 16carries out the preprocessing procedure by determining motion vectordata, and storing the motion vector data in the external memory 8, andcarries out the recording process by effecting a motion compensatingprocess using the motion vector data stored in the external memory 8without effecting a motion detecting process in the motion detector 3,and subtracting image information produced by the motion compensationfrom image information to be encoded. The image information recordingapparatus employs only the second memory 14 therein. Therefore, in thecase where the encoder 11 employs the variable-rate encoding process,the recording process can reliably be carried out. Since it is notnecessary in the recording process to effect a motion detecting processin the motion detector 3 which is of a large circuit scale, theconsumption of electric energy by the image information recordingapparatus is greatly reduced. Accordingly, the image informationrecording apparatus offers outstanding advantages in that it employs thevariable-rate encoding process for improved image quality, simplifiesthe overall process for largely reducing the consumption of electricenergy, and requires a minimized memory capacity.

Specific details of the second embodiment will be described below withreference to FIG. 17. In FIG. 16, the signal source 1 corresponds to thereproducer 52 shown in FIG. 6, the controller 7 corresponds to thesystem controller 59 shown in FIG. 6, the external memory 8 correspondsto the external memory 51 shown in FIG. 6, the recorder 17 correspondsto the master generator 58 shown in FIG. 6, and the remaining componentscorrespond to various circuits in the video encoder 55 shown in FIG. 6.

M. Another Structure and Operation of the Video Encoder Shown in FIG. 6

FIG. 17 is a block diagram of another internal structure of the videoencoder 55 shown in FIG. 6.

Structure:

The video encoder shown in FIG. 17 structurally differs from the videoencoder shown in FIG. 13 in that the video encoder shown in FIG. 17employs only the frame memories 101, 102 among the frame memories 101,102, 103 of the video encoder shown in FIG. 13, frame image data storedin the frame memories 101, 102 are used in the motion detecting processand the motion compensating process, motion detectors 305, 306 supplyread/write control signals respectively to the frame memories 119, 122,the motion detector 305 supplies a read/write control signal to theframe memories 101, 102, and the controller 128 controls the selector104 to selectively output the image data read from the frame memories101, 102.

Operation for Producing Motion Vector Data:

Operation of the video encoder shown in FIG. 17 for producing motionvector data will be described below.

For producing motion vector data, the controller 128 generates switchingcontrol signals based on control signals supplied from the systemcontroller 59 shown in FIG. 6 to connect the motion detector 305 and themotion compensator 120 and the motion detector 306 and the motioncompensator 123, and supplies the switching control signals to theswitches 121, 124, respectively, to connect the movable contacts "c"thereof to the respective fixed contacts "a".

Frame image data supplied to the input terminal 100 are suppliedsuccessively in the frame memories 101, 102, and also storedsuccessively in the frame memories 119, 122 through the selector 104,the switch 109, the DCT circuit 110, the quantizer 111, the inversequantizer 115, the IDCT circuit 116, the adder 117 (only for B and Ppictures), and the switch 11R.

The process of encoding the macroblock data outputted from the selector104 will be described below also with reference to FIGS. 15A and 15B.The frames in a GOP 2 shown in FIGS. 15A and 15B will be described byway of example below.

It is assumed that the frame memory 101 stores the image data I6 shownin FIG. 15A, the frame memory 1012 stores the image data B5 shown inFIG. 15A, the frame memory 122 stores the image data P4 used aspredictive image data for the image data B5 shown in FIG. 15A, and, forillustrative purpose, predictive image data from the 1/2 multiplier 126are used at all times for being encoded into B pictures.

The image data I6, shown in FIG. 15B, read from the frame memory 101 ofeach of macroblock data are outputted successively from the selector104. At this time, the movable contacts "c" of the switches 109, 118 areconnected to the fixed contacts "b" thereof. Therefore, the macroblockdata of the image data I6 pass through the switch 109, are processed bythe DCT circuit 110, the quantizer 111, the VLC encoder 112, and theoutput encoder 113, and are outputted from the output terminal 114.

Coefficient data of the image data I6 which are quantized by thequantizer 111 are converted back into the original macroblock datahaving a size of 8 lines×8 pixels by the inverse quantizer 115 and theIDCT circuit 116, and the original macroblock data are supplied throughthe switch 118 to the frame memory 119 and successively stored therein.

After the image data P4 are stored in the frame memory 122 and the imagedata I6 are stored in the frame memory 119, predictive image data fromthe 1/2 multiplier 126 are subtracted from the image data B5 outputtedfrom the selector 104 by the adder 107, which produces differential datathat are encoded.

The motion detector 305 effects a motion detecting process on eachmacroblock of the image data I6 stored in the frame memory 119 and eachmacroblock of the image data B5 stored in the frame memory 102,producing motor vector data indicative of which part (macroblock data)of the image data I6 is in agreement with each of the macroblocks of theimage data B5. The motion vector data of each macroblock are used in themotion compensator 120 to successively read the corresponding macroblockdata in the image data I6 stored in the frame memory 119, i.e., toeffect a motion compensating process.

The motion detector 306 effects a motion detecting process on eachmacroblock of the image data B5 stored in the frame memory 102 and eachmacroblock of the image data P4 stored in the frame memory 122,producing motor vector data indicative of which part (macroblock data)of the image data P4 is in agreement with each of the macroblocks of theimage data B5. The motion vector data of each macroblock are used in themotion compensator 123 to successively read the corresponding macroblockdata in the image data P4 stored in the frame memory 122, i.e., toeffect a motion compensating process.

As the macroblock data of the image data B5 are outputted from theselector 104, the 1/2 multiplier 126 outputs average data indicative ofthe average of the macroblock data of the motion-compensated image dataI6 from the motion compensator 120 and the macroblock data of themotion-compensated image data P4 from the motion compensator 123, andsupplies the average data through the switch 127 to the adder 107. Theadder 107 subtracts the supplied average data from the macroblock dataof the image data B5, thereby producing differential data that areencoded by the compressing and encoding block. The above process iscarried out with respect to all the macroblock data of the image dataB5.

Concurrent with the encoding process effected on the image data B5, theimage data I6 stored in the frame memory 119 are read therefrom andsupplied to the frame memory 122 and stored therein. Simultaneously, theimage data B5 as the sum output data from the adder 117 are suppliedthrough the switch 118 to the frame memory 118. The image data B7, P8supplied through the input terminal 100 are successively stored in theframe memories 102, 101.

The image data P8 are encoded next. For generating the image data of a Ppicture, the motion detector 305 supplies a read/write control signal toboth the frame memories 101, 102.

The motion detector 305 effects a motion detecting process on eachmacroblock of the image data B7 stored in the frame memory 102 and eachmacroblock of the image data P8 stored in the frame memory 101,producing motor vector data indicative of which part (macroblock data)of the image data P8 is in agreement with each of the macroblocks of theimage data B7. The motion vector data of each macroblock are used in themotion compensator 120 to successively read the corresponding macroblockdata in the image data I6 stored in the frame memory 122, i.e., toeffect a motion compensating process. It is to be noted that themacroblock data of the image data I6 are compensated for based on themotion vector data produced from the image data P8, B7.

As the macroblock data of the image data P8 read from the frame memory101 are selected by and outputted from the selector 104, themotion-compensated macroblock data of the image data I6 are suppliedfrom the motion compensator 120 through the switch 127 to the adder 107.Therefore, the adder 107 subtracts the motion-compensated macroblockdata of the image data I6 from the macroblock data of the image data P8,thereby producing differential data that are encoded by the compressingand encoding block and outputted from the output terminal 114. The aboveprocess is carried out with respect to all the macroblock data of theimage data P8. After the image data P8 are encoded, the image data I6stored in the frame memory 119 are stored in the frame memory 122.

During the above process, the encoded differential data from thequantizer 111 are converted back to the original differential data bythe inverse quantizer 115 and the IDCT circuit 116, and the originaldifferential data are supplied to the adder 117. The adder 117 adds theoriginal differential data and the motion-compensated macroblock datasupplied from the motion compensator 120 through the switch 127, thusconverting the differential data back to the macroblock data of theimage data P8. The macroblock data of the image data P8 are suppliedthrough the switch 118 to the frame memory 119. The above process iscarried out until the storage of the image data P8 into the frame memory119 is finished.

The image data B7 are encoded next. Before the image data B7 areoutputted from the selector 104, the image data P8 are stored in theframe memory 101, the image data B7 are stored in the frame memory 102,the image data P8 are stored in the frame memory 119, and the image dataI6 are stored in the frame memory 122.

The motion detector 305 effects a motion detecting process on eachmacroblock of the image data B7 stored in the frame memory 102 and eachmacroblock of the image data P8 stored in the frame memory 119,producing motor vector data indicative of which part (macroblock data)of the image data P8 is in agreement with each of the macroblocks of theimage data B7. The motion vector data of each macroblock are used in themotion compensator 120 to successively read the corresponding macroblockdata in the image data P8 stored in the frame memory 119, i.e., toeffect a motion compensating process.

The motion detector 306 effects a motion detecting process on eachmacroblock of the image data B7 stored in the frame memory 102 and eachmacroblock of the image data I6 stored in the frame memory 122,producing motor vector data indicative of which part (macroblock data)of the image data I6 is in agreement with each of the macroblocks of theimage data B7. The motion vector data of each macroblock are used in themotion compensator 123 to successively read the corresponding macroblockdata in the image data I6 stored in the frame memory 122, i.e., toeffect a motion compensating process.

As the macroblock data of the image data B7 are outputted from theselector 104, the 1/2 multiplier 126 outputs average data indicative ofthe average of the macroblock data of the motion-compensated image dataP8 from the motion compensator 120 and the macroblock data of themotion-compensated image data I6 from the motion compensator 123, andsupplies the average data through the switch 127 to the adder 107. Theadder 107 subtracts the supplied average data from the macroblock dataof the image data B7, thereby producing differential data that areencoded by the compressing and encoding block and outputted from theoutput terminal 114. The above process is carried out with respect toall the macroblock data of the image data B7. After the image data B7are encoded, the image data P8 stored in the frame memory 119 are storedin the frame memory 122.

The image data of each frame of the GOP 2 are encoded in the mannerdescribed above. The motion vector data produced by the motion detectors305, 306 are supplied through the output terminals 121o, 124o to thesystem controller 59 shown in FIG. 6.

The motion vector data supplied through the output terminals 121o, 124oto the system controller 59 are supplied through the system controller59 to the external memory 51 shown in FIG. 6, and stored therein.

The image data of the other GOPs are subjected to the motion detectingprocess and the encoding process in the same manner as described above.The controller 128 adds the motion vector data supplied from the motiondetectors 305, 306, data indicative of a motion compensation type (ordata indicative of the data subtracted in the encoding process), anddata indicative of a picture type to the compressed data or compresseddifferential data supplied to the output encoder 113, and also adds dataindicative of the start of each GOP and data indicative of the encodingorder to the compressed data or compressed differential data. Thecompressed data or compressed differential data to which the above dataare added are converted into data in a product code format by the outputencoder 113, and then outputted through the output terminal 128b andsupplied to the system controller 59 shown in FIG. 6. The number of bitsof each GOP of the compressed data or compressed differential datasupplied to the system controller 59 is detected by the GOP bit numberdetector 70 shown in FIG. 6.

Operation in Encoding Process:

Operation of the video encoder shown in FIG. 17 for encoding frame imagedata using the motion vector data stored in the external memory 51 willbe described below. Only the encoding of frame image data of a B picturewill be described.

In the encoding process, the controller 128 generates switching controlsignals based on control signals supplied from the system controller 59shown in FIG. 6 to connect the motion detector 305 to the motioncompensator 120 and disconnect the motion detector 306 from the motioncompensator 123, and supplies the switching control signals to theswitches 121, 124, respectively, to connect the movable contacts "c"thereof to the respective fixed contacts "b". The controller 128 alsosupplies control signals to the motion detectors 305, 306 to stop theirmotion detecting process based on the control signals supplied from thesystem controller 59. The motion detectors 305, 306 now stop theirmotion detecting process although they supply read/write control signalsto the frame memories 101, 102.

Under the control of the external memory controller 75 of the systemcontroller 59, motion vector data read from the external memory 51 andsupplied through the system controller 59 are supplied through the inputterminal 121i and the switch 121 to the motion compensator 120 andthrough the input terminal 124i and the switch 124 to the motioncompensator 123. The motion vector data are also supplied throughinput/output terminal 128b to the controller 128.

Image data supplied to the input terminal 100 are successively stored inthe frame memories 101, 102. The motion compensator 120 reads macroblockdata represented by the motion vector data supplied through the inputterminal 121i and the switch 121 from the frame memory 119. The motioncompensator 123 reads macroblock data represented by the motion vectordata supplied through the input terminal 124i and the switch 124 fromthe frame memory 122.

The macroblock data read from the frame memory 119 by the motioncompensator 120 and the macroblock data read from the frame memory 122by the motion compensator 123 are supplied to the adder 125, which addsthe supplied macroblock data. Sum output data from the adder 125 aresupplied to the 1/2 multiplier 126, which multiplies the supplied databy the coefficient "1/2", thus averaging the data. The average data aresupplied through the switch 127 to the adder 107, which subtracts theaverage data from the macroblock data of the present frame supplied fromthe selector 104, thus producing differential data. The differentialdata are supplied through the switch 109 to the DCT circuit 110, whichconverts the differential data into coefficient data ranging from DC toharmonic AC components. The coefficient data from the DCT circuit 110are supplied to the quantizer 111.

The quantization step size data QST from the system controller 59 aresupplied through the input/output terminal 128b to the controller 128,which supplies the quantization step size data QST to the quantizer 111.The quantizer 111 quantizes the coefficient data from the DCT circuit110 based on the quantization step size data QST.

The controller 128 adds the motion vector data supplied from theexternal memory 51 through the system controller 59, data indicative ofa motion compensation type (or data indicative of the data subtracted inthe encoding process), and data indicative of a picture type to thecompressed data or compressed differential data supplied to the outputencoder 113, and also adds data indicative of the start of each GOP anddata indicative of the encoding order to the compressed data orcompressed differential data. The compressed data or compresseddifferential data to which the above data are added are converted intodata in a product code format by the output encoder 113, and thenoutputted through the output terminal 114 and supplied through theinterface 57 to the master generator 58, which records the supplied dataon a master.

Advantages of 2nd embodiment

According to the second embodiment, the frame memories 119, 122 are usedin both the motion detecting process and the recording process.Therefore, the second embodiment offers an advantage in that one framememory may be dispensed with, in addition to the advantages offered bythe first embodiment.

3rd Embodiment:

N. Another Structure of the Digital Video Data Recording System Shown inFIG. 6

FIG. 18 shows a digital video data recording system according to a thirdembodiment of the present invention.

Structure

In FIG. 18, a reproducer 351 corresponds to the reproducer 52 shown inFIG. 6, an encoder 353 includes the DCT circuit 110, the quantizer 111,the VLC encoder 112, and the output encoder 113 shown in FIGS. 13 and17, a system controller 355 corresponds to the system controller 59shown in FIG. 6, external memories 358-1˜358-n correspond to theexternal memory 51 shown in FIG. 6, and encoders 361-1˜361-n arestructurally identical to the encoder 353.

The system controller 355 has an interface 357 which may comprise anSCSI2 interface, for example.

The external memories 358-1˜358-n correspond to respective materialswhich are recorded on a recording medium loaded in the reproducer 351,and store motion vector data which are determined with respect to thematerials. A resistor connected to the external memory 358-n serves as aterminator.

The encoders 361-1˜361-n correspond to the materials, and serve toencode the materials assigned by a selector 360 based on motion vectordata read from the external memories 358-1˜358-n. The encoders361-1˜361-n have respective input terminals I1˜In for entering motionvector data and quantization step size data supplied from the systemcontroller 355. The encoders 361-1˜361-n also have respective outputterminals O1˜On for supplying encoded data to the interface 57 shown inFIG. 6. Since the encoders 361-1˜361-n do not operate simultaneously,all the output terminals O1˜On may be connected to the input terminal ofthe interface 57.

In the digital video data recording system shown in FIG. 18, thereproducer 351 plays back a recording medium with a plurality ofmaterials recorded thereon. In a first cycle of operation, motion vectordata and quantization step size data are produced with respect to allthe materials, and the produced motion vector data are stored in theexternal memories 358-1˜358-n. In a second cycle of operation, all thematerials are encoded by the encoders 361-1˜361-n using the motionvector data read from the external memories 358-1˜358-n and thequantization step size data stored in an internal memory.

Operation for Producing Motion Vector Data:

A switch 352 has a movable contact "c" which is connected to a fixedcontact "a" thereof by a switching control signal from the systemcontroller 355. Then, the reproducer 351 is brought into a playback modeby a control signal from the system controller 355. A plurality ofmaterials are recorded on a recording medium which is loaded in thereproducer 351. Therefore, the materials are successively reproduced bythe reproducer 351, and supplied through the switch 352 to the encoder353 and a motion detector 354. The motion detector 354 effects a motiondetecting process on the reproduced materials to produce motion vectordata which re supplied to the encoder 353 and a controller 356. Thecontroller 356 supplies the motion vector data from the motion detector354 to the external memories 358-1˜358-n, which store the suppliedmotion vector data.

The encoder 353 encodes the materials supplied through the switch 352,using the motion vector data from the motion detector 354. Encoded dataoutputted from the encoder 353 are supplied to the controller 356. Thecontroller 356 detects the number of bits of the encoded data for eachGOP thereby to produce quantization step size data, and registers thequantization step size data in a recording table (see FIG. 19) stored inan internal memory. The system controller 355 stops the playback mode ofthe reproducer 351 when it recognizes that the above process is finishedwith respect to all the materials.

Operation in Encoding Process for Recording Materials:

In the encoding process for recording the materials, the movable contact"c" of the switch 352 is connected to another fixed contact "b" by aswitching control signal from the system controller 355. Therefore, thematerials reproduced by the reproducer 351 are supplied through theswitch 352 and the selector 360 to the encoders 361-1˜361n whichcorrespond to the materials to be processed.

The encoders 361-1˜361-n are supplied with the motion vector data readfrom the external memories 358-1˜358-n corresponding to the materials tobe processed and also with the quantization step size data through theinput terminals I1˜In under the control of the system controller 355.The reproduced materials from the reproducer 351 are now encoded by theencoders 361-1˜361-n using the motion vector data read from the externalmemories 358-1˜358-n and the quantization step size data. Encoded dataare outputted from the output terminals O1˜On, supplied through theinterface 57 shown in FIG. 6 to the master generator 58, and recorded onthe recording medium set in the master generator 58.

O. Table Data in the Digital Video Data Recording System Shown in FIG.18

FIG. 19 shows the recording table used in the digital video datarecording system shown in FIG. 18.

As shown in FIG. 19, the recording table is stored in the internalmemory of the system controller 355 of the digital video data recordingsystem shown in FIG. 18, and is updated from time to time duringoperation thereof. The recording table contains material ID data,material information, external memory ID data, external memoryinformation, encoding selection information, and status.

The material ID data are data for identifying the materials describedabove. The material information is the same as the information that iscontained in the time code table shown in FIG. 7A and the GOP tableshown in FIG. 7B. The external memory ID data comprise data foridentifying the external memories 358-1˜358-n shown in FIG. 18. Theexternal memory information is the same as the information contained inthe hard disk table shown in FIG. 7C, and kept in association with therespective external memory ID data. The encoding selection informationcomprises information representing association between the externalmemories 358-1˜358-n and the encoders 361-1˜361-n. In this embodiment,the external memory 358-1 and the encoder 361-1, the external memory358-2 and the encoder 361-2, . . . , and the external memory 358-n andthe encoder 361-n are associated with each other. The status comprisesinformation indicating either an unprocessed status, a motion detectedstatus, or a recorded status. For example, the unprocessed status isrepresented by "00", the motion detected status by "01", and therecorded status by "10".

P. Operation of the Digital Video Data Recording System Shown in FIG. 18

FIGS. 20 and 21 show an operation sequence of the digital video datarecording system shown in FIG. 18. Details of some steps are the same asthose of the flowcharts shown in FIGS. 9 through 12.

In a step S200 shown in FIG. 20, the system controller 355 supplies aswitching control signal to the switch 352, connecting the movablecontact "c" to the fixed contact "a" thereof. Then, control proceeds toa step S201.

In the step S201, the system controller 355 reads the data stored in therecording table. Then, control proceeds to a step S202.

In the step S202, the system controller 355 writes "1" in a storage areafor material number data IDd representing the number of processedmaterials, in the storage space of the internal memory thereof.Thereafter, control proceeds to a step S203.

In the step S203, the system controller 355 effects various controlprocesses on the reproducer 351 to access the start of a material, andthe reproducer 351 accesses the start of the material. Then, controlproceeds to a step S204. The processing operation of the step S203 isthe same as that of the steps S102, S103 shown in FIG. 11.

In the step S204, the system controller 355 supplies a control signalrepresenting a playback mode to the reproducer 351 for thereby causingthe reproducer 351 to start the playback mode. Then, control proceeds toa step S205. The processing operation of the step S204 is the same asthat of the step S104 shown in FIG. 11.

In the step S205, the system controller 355 supplies the external memoryID, the external memory information, and the motion vector data from themotion detector 354 to the external memory 351-1, 351-2, . . . , or351-n which corresponds the material being processed. The motion vectordata are stored in the external memory 351-1, 351-2, . . . , or 351-n.Then, control proceeds to a step S206.

In the step S206, the system controller 355 detects the number of bitsof encoded data supplied from the encoder 353 for each GOP, producingquantization step size data. Thereafter, control proceeds to a stepS207.

In the step S207, the system controller 355 reads time code data fromthe reproducer 351. Then, control proceeds to a step S208.

In the step S208, the system controller 355 decides whether the end ofthe material is reached or not. If the end of the material is reached(YES), then control proceeds to a step S209. If the end of the materialis not reached (NO), then control goes back to the step S205. Theprocessing operation of the step S208 is the same as that of the stepS109 shown in FIG. 11.

In the step S209, the system controller 355 supplies a control signalindicative of a pause mode to the reproducer 351 to bring the reproducer351 into a pause mode. Then, control proceeds to a step S210.

In the step S210, the system controller 355 increments, by "1", thenumerical data stored in the storage area for material number data IDd,and writes new incremented numerical data in the same storage area.Then, control proceeds to a step S211.

In the step S211, the system controller 355 detects the number ofmaterials registered in the recording table, and increments thenumerical value representing the detected number of materials by "1".The system controller 355 reads the material number data IDd from theinternal memory thereof, and decides whether the material number dataIDd are equal to the incremented numerical value or not. If the materialnumber data IDd are equal to the incremented numerical value (YES), thencontrol goes to a step S212 shown in FIG. 21. If the material numberdata IDd are not equal to the incremented numerical value (NO), thencontrol goes back to the step S203. The processing operation of the stepS211 serves to decide whether all the materials to be recorded, whichare registered in the recording table, have been processed or not.

In the step S212, the system controller 355 supplies a switching controlsignal to the switch 352, connecting the movable contact "c" to thefixed contact "b" thereof. Then, control proceeds to a step S213.

In the step S213, the system controller 355 reads the data stored in therecording table. Then, control proceeds to a step S214.

In the step S214, the system controller 355 writes "1" in the storagearea for material number data IDd representing the number of processedmaterials, in the storage space of the internal memory thereof.Thereafter, control proceeds to a step S215.

In the step S215, the system controller 355 supplies the selector 360with a control signal for selecting the encoder 361-1, 361-2, . . . , or361-n which corresponds to a material to be processed. Then, controlproceeds to a step S216.

In the step S216, the system controller 355 effects various controlprocesses on the reproducer 351 to access the start of the material, andthe reproducer 351 accesses the start of the material. Then, controlproceeds to a step S217. The processing operation of the step S216 isthe same as that of the steps S102, S103 shown in FIG. 11.

In the step S217, the system controller 355 supplies a control signalrepresenting a playback mode to the reproducer 351 for thereby causingthe reproducer 351 to start the playback mode. Then, control proceeds toa step S218. The processing operation of the step S217 is the same asthat of the step S104 shown in FIG. 11.

In the step S218, the system controller 355 supplies the external memoryID and the external memory information to the external memory 351-1,351-2, . . . , or 351-n which corresponds the material being processed.The motion vector data are now retrieved from the external memory 351-1,351-2, . . . , or 351-n which corresponds the material to be processed.The retrieved motion vector data are supplied to the system controller355. Then, control proceeds to a step S219.

In the step S219, the system controller 355 supplies the retrievedmotion vector data and the quantization step size data registered in therecording table to the corresponding encoders 361-1, 361-2, . . . , or361-n. Thereafter, control proceeds to a step S220.

In the step S220, the system controller 355 reads time code data fromthe reproducer 351. Then, control proceeds to a step S221.

In the step S221, the system controller 355 decides whether the end ofthe material is reached or not. If the end of the material is reached(YES), then control proceeds to a step S222. If the end of the materialis not reached (NO), then control goes back to the step S218. Theprocessing operation of the step S221 is the same as that of the stepS109 shown in FIG. 11.

In the step S222, the system controller 355 supplies a control signalindicative of a pause mode to the reproducer 351 to bring the reproducer351 into a pause mode. Then, control proceeds to a step S223.

In the step S223, the system controller 355 increments, by "1", thenumerical data stored in the storage area for material number data IDd,and writes new incremented numerical data in the same storage area.Then, control proceeds to a step S224.

In the step S224, the system controller 355 detects the number ofmaterials registered in the recording table, and increments thenumerical value representing the detected number of materials by "1".The system controller 355 reads the material number data IDd from theinternal memory thereof, and decides whether the material number dataIDd are equal to the incremented numerical value or not. If the materialnumber data IDd are equal to the incremented numerical value (YES), thencontrol comes to an end. If the material number data IDd are not equalto the incremented numerical value (NO), then control goes back to thestep S215. The processing operation of the step S224 serves to decidewhether all the materials to be recorded, which are registered in therecording table, have been recorded or not.

Advantages of Third Embodiment:

In the third embodiment, the recording medium with plural materialsrecorded thereon is played back by the reproducer 351. In the firstcycle of operation, motion vector data and quantization step size dataare produced with respect to all the materials that are reproduced, andthe produced motion vector data are stored in the external memories358-1˜358-n corresponding to the respective materials. In the secondcycle of operation, all the reproduced materials are encoded by thecorresponding encoders 361-1˜361-n using the motion vector data readfrom the external memories 358-1˜358-n and the quantization step sizedata stored in the internal memory of the system controller. Therefore,the third embodiment offers an advantage in that the plural materialscan successively be processed and only one motion detector is required,in addition of the advantages offered by the first embodiment.

4th Embodiment:

Q. Another Structure of the Digital Video Data Recording System Shown inFIG. 6

FIG. 22 shows a digital video data recording system according to afourth embodiment of the present invention.

Structure:

In FIG. 22, a plurality of reproducers 351-1˜351-n correspond to thereproducer 52 shown in FIG. 6, an encoder 353 includes the DCT circuit110, the quantizer 111, the VLC encoder 112, and the output encoder 113shown in FIGS. 13 and 17, a system controller 355 corresponds to thesystem controller 59 shown in FIG. 6, external memories 358-1˜358-ncorrespond to the external memory 51 shown in FIG. 6, and encoders361-1˜361-n are structurally identical to the encoder 353.

The system controller 355 has an interface 357 which may comprise anSCSI2 interface, for example.

The external memories 358-1˜358-n correspond to respective materialswhich are recorded on recording mediums loaded in the reproducers351-1˜351-n, and store motion vector data which are determined withrespect to the materials. A resistor connected to the external memory358-n serves as a terminator.

The encoders 361-1˜361-n correspond to the materials, and serve toencode the materials assigned by a selector 360 based on motion vectordata read from the external memories 358-1˜358-n. The encoders361-1˜361-n have respective input terminals I1˜In for entering motionvector data and quantization step size data supplied from the systemcontroller 355. The encoders 361-1˜361-n also have respective outputterminals O1˜On for supplying encoded data to the interface 57 shown inFIG. 6. All the output terminals O1˜On may be connected to the inputterminal of the interface 57.

In the digital video data recording system shown in FIG. 22, thereproducers 351-1˜351-n play back respective recording mediums. In afirst cycle of operation, motion vector data and quantization step sizedata are produced with respect to all the materials, and the producedmotion vector data are stored in the external memories 358-1˜358-n. In asecond cycle of operation, all the materials are encoded by the encoders361-1˜361-n using the motion vector data read from the external memories358-1˜358-n and the quantization step size data stored in an internalmemory.

Operation for Producing Motion Vector Data:

One of the reproducers 351-1˜351-n is brought into a playback mode by acontrol signal from the system controller 355, and reproduced data fromthe reproducer in the playback mode are supplied through a selector 360to the encoder 353 and a motion detector 354. The motion detector 354effects a motion detecting process on the reproduced materials toproduce motion vector data which re supplied to the encoder 353 and acontroller 356. The controller 356 supplies the motion vector data fromthe motion detector 354 to the external memories 358-1˜358-n, whichstore the supplied motion vector data.

The encoder 353 encodes the materials supplied through the selector 360,using the motion vector data from the motion detector 354. Encoded dataoutputted from the encoder 353 are supplied to the controller 356. Thecontroller 356 detects the number of bits of the encoded data for eachGOP thereby to produce quantization step size data, and registers thequantization step size data in a recording table stored in an internalmemory.

Operation in Encoding Process for Recording Materials:

In the encoding process for recording the materials, the reproducedmaterial from either one of the reproducers 351-1˜351-n is suppliedthrough the selector 360 to the encoders 361-1˜361-n which correspond tothe materials to be processed, according to a control signal from thesystem controller 355.

The encoders 361-1˜361-n are supplied with the motion vector data readfrom the external memories 358-1˜358-n corresponding to the materials tobe processed and also with the quantization step size data through theinput terminals I1˜In under the control of the system controller 355.The reproduced materials from the reproducer 351 are now encoded by theencoders 361-1˜361-n using the motion vector data read from the externalmemories 358-1˜358-n and the quantization step size data. Encoded dataare outputted from the output terminals O1˜On, supplied through theinterface 57 shown in FIG. 6 to the master generator 58, and recorded onthe recording medium set in the master generator 58.

R. Table Data in the Digital Video Data Recording System Shown in FIG.22

The recording table is stored in the internal memory of the systemcontroller 355 of the digital video data recording system shown in FIG.22, and is updated from time to time during operation thereof. Therecording table contains material ID data, material information,external memory ID data, external memory information, encoding selectioninformation, and status.

The material ID data are data for identifying the materials describedabove. The material information is the same as the information that iscontained in the time code table shown in FIG. 7A and the GOP tableshown in FIG. 7B, and serves to identify the reproducers 351-1˜351-n.The external memory ID data comprise data for identifying the externalmemories 358-1˜358-n shown in FIG. 22. The external memory informationis the same as the information contained in the hard disk table shown inFIG. 7C, and kept in association with the respective external memory IDdata. The encoding selection information comprises informationrepresenting association between the external memories 358-1˜358-n andthe encoders 361-1˜361-n. In this embodiment, the external memory 358-1and the encoder 361-1, the external memory 358-2 and the encoder 361-2,. . . , and the external memory 358-n and the encoder 361-n areassociated with each other. The status comprises information indicatingeither an unprocessed status, a motion detected status, or a recordedstatus. For example, the unprocessed status is represented by "00", themotion detected status by "01", and the recorded status by "10".

Modifications:

In the first through fourth embodiments, a quantization step size isdetermined with respect to each GOP. However, a quantization step sizemay determined with respect to each macroblock, each field, eachoptional number of frames, or each group of N GOPs. In any case, if theamount of data with respect to which a quantization step size is to bedetermined is larger (e.g., each group of N GOPs), then greater meritsresult from the fixed-rate encoding process, and if the amount of datawith respect to which a quantization step size is to be determined issmaller (e.g., each macroblock), then greater merits result from thevariable-rate encoding process.

In the first through fourth embodiments, the inter-frame encodingprocess and the intra-frame encoding process have been described.However, inter-field and intra-field encoding processes offersubstantially the same advantages as with the inter-frame andintra-frame encoding processes in the first through fourth embodiments,except that the variable-rate encoding process is more advantageousbecause of the processing with respect to each field.

In the first through fourth embodiments, the data after they are encodedfor outputting purpose are counted for each GOP. However, the data afterthey are VLC-encoded or quantized may be counted for each GOP. In such amodification, it is necessary to subtract the decoded information andthe parity data from the amount of all data recordable on the recordingmedium, and establish quantization step size data for each GOP such thatthe amount of data after they are quantized or VLC-encoded fall withinthe differential amount of data recordable on the recording medium. Thepresent invention has been described above as being embodied in a methodof and a system for recording image information and also a method of anda system for encoding image information. However, the principles of thepresent invention are also applicable to a system for transmittingencoded image information to a transmission path, rather than recordingthe encoded image information on a recording medium. In this case, theamount of information may be assigned such that an amount of informationin the amount of information usable in the transmission path is assignedbased on the amount of encoded image information in each given unit(e.g., each GOP).

According to the present invention, as described above, before imageinformation from the signal source is recorded on the recording mediumby the recorder, motion vector information produced by the motiondetector is stored in the memory, and the amount of information withrespect to an encoding unit of encoded information from the encoder isdetermined. Based on the determined amount of information and the amountof information recordable on the recording medium, compression rationinformation indicative of a compression ratio at the encoder in therecording process is determined in the encoding unit. When the imageinformation from the signal source is recorded on the recording mediumby the recorder, the motion vector information stored in the memory isread, and the read motion vector information and the compression ratioinformation are supplied to the encoder. Therefore, in a preprocessingprocedure prior to the recording process, it is possible to obtain themotion vector information and the compression ratio information in theencoding unit of all the image information for recording all the imageinformation from the signal source on the recording medium. In therecording process, the image information is encoded using the motionvector information and the compression ratio information, and recordedon the recording medium. Therefore, it is not necessary for the motiondetector to effect a motion detecting process in the recording process,and hence an undue consumption of electric energy is reduced.Furthermore, the image information from the signal source can be encodedin an optimum amount of information, and can all be recorded on therecording medium, and images reproduced from the recorded imageinformation have a high quality.

Having described preferred embodiments of the invention with referenceto the accompanying drawings, it is to be understood that the inventionis not limited to those precise embodiments and that various changes andmodifications could be effected by one skilled in the art withoutdeparting from the spirit or scope of the invention as defined in theappended claims.

What is claimed is:
 1. A method of recording image information on arecording medium, comprising the steps of:storing motion vectorinformation produced by detecting a motion of image informationoutputted from a signal source; detecting an amount of encoded imageinformation, in each of a plurality of predetermined units, produced byencoding the image information outputted from the signal source usingsaid motion vector information; assigning an amount of information inthe amount of information recordable on the recording medium to imageinformation in each of said plurality of predetermined units based onthe amount of encoded image information in said predetermined unit;obtaining compression ratio information representing a compression ratioused for each of said plurality of predetermined units when the imageinformation is encoded, based on the assigned amount of information;encoding the image information of each of said plurality ofpredetermined units outputted from the signal source using said motionvector information and said compression ratio information for each ofsaid plurality of predetermined units; and recording the imageinformation thus encoded on the recording medium.
 2. The methodaccording to claim 1, wherein said compression ratio informationrepresents a quantization step size.
 3. The system for recording imageinformation on a recording medium, comprising:motion detecting means fordetecting a motion of image information outputted from a signal sourceto produce motion vector information; memory means for storing themotion vector information produced by said motion detecting means;encoding means for encoding the image information outputted from thesignal source based on the motion vector information produced by saidmotion detecting means or the motion vector information stored in saidmemory means; recording means for recording the image informationencoded by said encoding means on the recording medium; and controlmeans for controlling said motion detecting means, said memory means,said encoding means, and said recording means; said control meanscomprising:means for storing the motion vector information produced bysaid motion detecting means in said memory means, for determining anamount of information in each of a plurality of predetermined units ofthe encoded image information from said encoding means, and fordetermining compression ratio information representing a compressionratio in said encoding means for recording the image information foreach of said plurality of predetermined units with respect to all imageinformation to be recorded, based on the determined amount ofinformation for each of said plurality of predetermined units and atotal amount of information recordable on the recording medium, beforethe image information outputted from the signal source is recorded onthe recording medium by said recording means; and means for reading themotion vector information from said memory means and supplying the readmotion vector information and said compression ratio information foreach of said plurality of predetermined units to said encoding meanswhen the image information outputted from the signal source is recordedon the recording medium by said recording means.
 4. The system accordingto claim 3, wherein said compression ratio information represents aquantization step size.
 5. The system for recording image information ona recording medium, comprising:first memory means for storing imageinformation outputted from a signal source; motion detecting means foreffecting a motion detecting process on main image information from thesignal source and auxiliary image information from said first memorymeans to produce motion vector information; vector information memorymeans for storing the motion vector information produced by said motiondetecting means; encoding means for encoding the image informationoutputted from the signal source; recording means for recording theimage information encoded by said encoding means on the recordingmedium; decoding means for decoding the image information encoded bysaid encoding means; second memory means for storing the imageinformation decoded by said decoding means; motion compensating meansfor reading image information represented by the motion vectorinformation produced by said motion detecting means, from said secondmemory means; first adding means for subtracting the auxiliary imageinformation read by said motion compensating means from the main imageinformation from the signal source; second adding means for adding theimage information decoded by said decoding means and the auxiliary imageinformation read by said motion compensating means; and control meansfor detecting the amount of the image information encoded by saidencoding means, for obtaining compression ratio informationrepresentative of a compression ratio in said encoding means based onthe detected amount of the image information for each of a plurality ofpredetermined portions of said image information, for supplying thecompression ratio information to said encoding means to control thecompression ratio in said encoding means for each of said plurality ofpredetermined portions of said image information, and for controllingsaid first memory means, said motion detecting means, said vectorinformation memory means, said encoding means, said recording means,said decoding means, said second memory means, said motion compensatingmeans, said first adding means, and said second adding means; saidcontrol means comprising:means for controlling said motion detectingmeans to produce the motion vector information, for detecting the amountof the image information encoded by said encoding means, and forcalculating compression ratios of all the image information to berecorded for each of said Plurality of predetermined portions of saidimage information based at least on the total detected amount of theimage information and an amount of information recordable on therecording medium, in a preprocessing procedure for producing the motionvector information and calculating the compression ratio in the encodingmeans for each of said plurality of predetermined portions of said imageinformation; and means for supplying the motion vector information readfrom said vector information memory means to said motion compensatingmeans to use the motion vector information in said motion compensatingmeans, and for controlling the compression ratio in said encoding meansfor each of said plurality of predetermined portions of said imageinformation, when the image information outputted from the signal sourceis recorded on the recording medium by said recording means.
 6. Thesystem according to claim 5, said control means furthercomprising:amount-of-information detecting means for detecting an amountof information in each of said predetermined portions of the imageinformation; compression ratio calculating means for obtainingcompression ratio information representative of a compression ratio foreach of said Plurality of predetermined portions of said imageinformation with respect to the image information from the signalsource, based on the encoded image information for each of saidplurality of predetermined portions of said image information and theamount of information recordable on the recording medium; memory controlmeans for storing the motion vector information in said vectorinformation memory means and reading the motion vector informationstored in said vector information memory means; and table informationmemory means for storing a table of the information produced in saidpreprocessing procedure and the information required when the imageinformation outputted from the signal source is recorded on therecording medium by said recording means.
 7. The system according toclaim 5, wherein said signal source comprises a reproducer for playingback a recording medium, and said recording medium recordable by saidrecording means comprises a master for manufacturing a stamper.
 8. Thesystem according to claim 7, wherein said table contains at leastidentification information for identifying materials recorded on therecording medium played back by said reproducer, positional informationindicative of positions of the materials on the recording medium,amount-of-information information detected by said amount-of-informationdetecting means, compression ratio information produced by saidcompression ratio calculating means, and positional information of themotion vector information in said vector information memory means. 9.The system according to claim 5, wherein said compression ratioinformation represents a quantization step size.
 10. The system forrecording image information on a recording medium, comprising:memorymeans for storing image information outputted from a signal source;motion detecting means for effecting a motion detecting process on mainimage information from the signal source and auxiliary image informationfrom said first memory means to produce motion vector information;vector information memory means for storing the motion vectorinformation produced by said motion detecting means; encoding means forencoding the image information outputted from the signal source;recording means for recording the image information encoded by saidencoding means on the recording medium; decoding means for decoding theimage information encoded by said encoding means, supplying the decodedinformation to said memory means, and storing the decoded information insaid memory means; motion compensating means for reading imageinformation represented by the motion vector information produced bysaid motion detecting means, from said memory means; first adding meansfor subtracting the auxiliary image information read by said motioncompensating means from the main image information from the signalsource; second adding means for adding the image information decoded bysaid decoding means and the auxiliary image information read by saidmotion compensating means; and control means for detecting the totalamount of the image information encoded by said encoding means and theamount of the image information encoded by said encoding means for eachof a plurality of predetermined units of image information, forobtaining compression ratio information representative of a compressionratio in said encoding means for each of said plurality of predeterminedunits of image information based on the detected amount of the imageinformation, for supplying the compression ratio information for each ofsaid plurality of predetermined units of image information to saidencoding means to control the compression ratio in said encoding means,and for controlling said memory means, said motion detecting means, saidvector information memory means, said encoding means, said recordingmeans, said decoding means, said motion compensating means, said firstadding means, and said second adding means; said control meanscomprising:means for controlling said motion detecting means to producethe motion vector information, for detecting the amount of the imageinformation encoded by said encoding means for each of said plurality ofpredetermined units of image information, and for calculatingcompression ratios of all the image information to be recorded, for eachof said plurality of predetermined units of image information based onthe detected amount of the image information and an amount ofinformation recordable on the recording medium, in a preprocessingprocedure for producing the motion vector information and calculatingthe compression ratio in the encoding means; and means for supplying themotion vector information read from said vector information memory meansto said motion compensating means to use the motion vector informationin said motion compensating means, and for controlling the compressionratio in said encoding means for each of said plurality of predeterminedunits of image information, when the image information outputted fromthe signal source is recorded on the recording medium by said recordingmeans.
 11. The system according to claim 10, said control means furthercomprising:amount-of-information detecting means for detecting an amountof information in each of said plurality of predetermined units of theencoded image information; compression ratio calculating means forobtaining compression ratio information representative of a compressionratio for each of said plurality of predetermined units of imageinformation with respect to the image information from the signalsource, based on the encoded image information in each of said pluralityof predetermined units and the amount of information recordable on therecording medium; memory control means for storing the motion vectorinformation in said vector information memory means and reading themotion vector information stored in said vector information memorymeans; and table information memory means for storing a table of theinformation produced in said preprocessing procedure and the informationrequired when the image information outputted from the signal source isrecorded on the recording medium by said recording means.
 12. The systemaccording to claim 10, wherein said signal source comprises a reproducerfor playing back a recording medium, and said recording mediumrecordable by said recording means comprises a master for manufacturinga stamper.
 13. The system according to claim 12, wherein said tablecontains at least identification information for identifying materialsrecorded on the recording medium played back by said reproducer,positional information indicative of positions of the materials on therecording medium, amount-of-information information detected by saidamount-of-information detecting means, compression ratio informationproduced by said compression ratio calculating means, and positionalinformation of the motion vector information in said vector informationmemory means.
 14. The system according to claim 10, wherein saidcompression ratio information represents a quantization step size.
 15. Amethod of encoding image information, comprising the steps of:storingmotion vector information produced by detecting a motion of imageinformation outputted from a signal source; detecting an amount ofencoded image information, in each of a plurality of predeterminedunits, produced by encoding the image information outputted from thesignal source using said motion vector information; assigning an amountof information in the amount of information usable on a recording mediumto image information in each of said plurality of predetermined unitsbased on the amount of encoded image information in each of saidplurality of predetermined units; obtaining compression ratioinformation for each of said plurality of predetermined unitsrepresenting a compression ratio used when the image information isencoded, based on the assigned amount of information; and encoding theimage information outputted from the signal source using said motionvector information and said compression ratio information.
 16. A methodaccording to claim 15, wherein said compression ratio informationrepresents a quantization step size.
 17. The system for encoding imageinformation, comprising:motion detecting means for detecting a motion ofimage information outputted from a signal source to produce motionvector information; memory means for storing the motion vectorinformation produced by said motion detecting means; encoding means forencoding the image information outputted from the signal source based onthe motion vector information produced by said motion detecting means orthe motion vector information stored in said memory means; and controlmeans for controlling said motion detecting means, said memory means,and said encoding means; said control means comprising:means for storingthe motion vector information produced by said motion detecting means insaid memory means, for determining an amount of information in each of aplurality of predetermined units of the encoded image information fromsaid encoding means, and for determining compression ratio informationrepresenting a compression ratio in said encoding means for each of saidpredetermined units with respect to the total image information to berecorded, based on the total amount of information to be recorded and ausable amount of information; and means for reading the motion vectorinformation from said memory means and supplying the read motion vectorinformation and said compression ratio information to said encodingmeans.
 18. A system according to claim 17, wherein said compressionratio information represents a quantization step size.